The retribution tree is focused exclusively on increasing your damage. Those who wish to engage in PVP or any other type of melee will want to spec very deeply in this tree. Unfortunately, it is so focused on fighting that your other roles like healing or supporting will be severally weakened.
Tier 1
Name:
Improved Blessing of Might
Description:
Increases the attack power from Blessing of Might by a percentage.
Ranks:
Rank 1- 4%
Rank 2- 8%
Rank 3- 12%
Rank 4- 16%
Rank 5- 20%
Usefulness:

Commentary:
Since this is a tier one talent it is rather weak. Some raids have their paladins fill this talent out for buffing the entire party because every bit helps. It can also be useful when leveling if you are going to be relying heavily on melee.

Benediction
Description:
Reduces the mana cost of your Judgment and Seals by a percentage.
Ranks:
Rank 1- 3%
Rank 2- 6%
Rank 3- 9%
Rank 4- 12%
Rank 5- 15%
Usefulness:

Commentary:
One method of damage dealing for paladins is to juggle seals and judgments, but this costs more mana then simply swinging your mace. I prefer this style of combat and found that over a long session of grinding mana efficiency is worth more then a boost to attack power.

Improved Judgment
Description:
Decreases the cooldown of your Judgment ability.
Ranks:
Rank 1- Decreases cooldown by 1 second.
Rank 2- Decreases cooldown by 2 seconds.
Usefulness:

Commentary:
This may not seem like much but this is a really great talent, especially in PVP or when you are fighting multiple mobs. I always put points in it as soon as possible.

Improved Seal of the Crusader
Description:
Increases the chance that while this judgment is up, your target will be struck by a critical strike from all attacks by a percentage.
Ranks:
Rank 1- 1%
Rank 2- 2%
Rank 3- 3%
Usefulness:

Commentary:

This can be an absolutely incredible buff if you are in a large raid. Giving everyone there an extra three percent spell and melee crit is a huge boost to DPS. The only problem is that you will have to either reapply the judgment throughout the fight, or melee to refresh it. This will make it harder for your to heal or tank, but if your raid lets you run as a ret spec then grab it.

Deflection
Description:
Increases your parry chance by a percentage.
Ranks:
Rank 1- 1% increase to parry.
Rank 2- 2% increase to parry.
Rank 3- 3% increase to parry.
Rank 4- 4% increase to parry.
Rank 5- 5% increase to parry.
Usefulness:

Commentary:
This is a nice talent, but I don’t care for the fact that it takes one point for one percentage. It seems rather costly when I could put points into other talents. It is also oriented to increasing your defense, not your offensive abilities which could be a good thing or bad thing depending on your skill and gear. If I do put points in this it is only to gain access to tier 3. If you are playing as a tank and are going into ret for a support tree then get all five.

Vindication
Description:
Gives a chance for your damaging attacks to reduce all of your opponents stats by a percentage..
Ranks:
Rank 1- 5% decrease to all stats..
Rank 2- 10% decrease to all stats.
Rank 3- 15 % decrease to all stats..
Usefulness:

Commentary:
This is primarily a PVP talent as its uses in PVE are somewhat limited. It will hinder your enemy a bit though which can bring them down to your level. But I usually don’t bother with it because there are other better talents in tier 3. I will sometimes put at least one point in it so I can get the effect though.

Conviction
Description:
Increases your chance to land a critical strike by a percentage.
Ranks:
Rank 1- 1% increase.
Rank 2- 2% increase.
Rank 3- 3% increase.
Rank 4- 4% increase.
Rank 5- 5% increase.
Usefulness:

Commentary:
There is nothing to dislike about this talent. It is a must for melee centered fighters and still very useful for holy based fighters. It is also a requirement for Vengeance so if you spec deep into the Retribution tree you’ll need this.

Seal of Command.
Description:
Gives the paladin a chance to deal additional holy damage equal to 70% of normal weapon damage. Judging this seal will blast the target with holy damage, double if the target is stunned.
Ranks:
Rank 1- 68-74 holy damage when judged. 137-147 against stunned.
Rank 2- 64-70 holy damage when judged. 194-210 against stunned
Rank 3- 82-90 holy damage when judged. 248-270 against stunned
Rank 4- 85-95 holy damage when judged. 257-284 against stunned
Rank 5- 105-126 holy damage when judged. 315-348 against stunned
Rank 6- 289-320 holy damage when judged. 579-639 against stunned
Usefulness:

Commentary:
This is the most important tool a paladin can have for DPSing and without this your damage will be severely limited. It has a proc per minute chance of 7. So over the course of one minute you will get seven command strikes. It is also dependant on your weapons damage so it is best to use a heavy and slow two hander. Unleashing it will deal about the same damage as an equal ranked Judgment of Righteousness, so you will want to only to judge it when the enemy is stunned, usually from your Hammer of Justice.

Pursuit of Justice
Description:
Reduces the chance you will be hit with spells and increases your movement speed by a small amount.
Ranks:
Rank 1- 1% chance to not be hit by spells,movement speed increased by 5%
Rank 2- 2% chance to not be hit by spells,movement speed increased by 10%
Rank 3- 3% chance to not be hit by spells,movement speed increased by 15%
Usefulness:

Commentary:
I absolutely hate wasting time running so I usually put points in this just to save time. In all honesty it is only moderately useful, but it also has a low cost. It is best used in a PVP situation where you will be taking lots of spell damage and you need to keep with your opponent. Ironically enough though, one of its best uses is not pursuing justice but running away from enemies. It will often give you just enough of a buffer so that you will be out of attack range while fleeing.

Eye for an Eye.
Description:
When you are hit by a critical spell strike a portion of the damage you take will be returned to the caster. The damage won’t exceed 50% of your health.
Ranks:
Rank 1- 15% damage return.
Rank 2- 30% damage return.
Usefulness:

Commentary:
In PVP this is a casters worst nightmare. It is entirely dependant on being hit by critical strikes, so it more of a defensive ability then an offensive one and you have no control over it. Its mainly useful in PVP where casters depend heavily on critical strikes, but it is not very useful in PVE or leveling.

Improved Retribution Aura
Description:
Increases the damage done by Retribution Aura.
Ranks:
Rank 1- Damage increased by 25%
Rank 2- Damage increased by 50%.
Usefulness:

Commentary:
Retribution Aura is one of our best Auras and especially useful for fighting fast hitting melee characters. While it truly shines in PVP, I found that when soloing or grinding it is still very useful. If you are prot spec and are using ret as a support tree, you will also want to put point in this for the extra holy damage and threat. It also only costs two points, and its one of the few talents worth getting to gain access to tier 5.

Crusade
Description:
Increases all damage caused against humanoids, demons, undead and elementals by a percentage.
Ranks:
Rank one- 1%
Rank two- 2%
Rank three- 3%
Usefulness:

Commentary:
The amount of damage you gain from this is not worth the investment of three talent points. The only reason to put points in this is to have access to the next tier, but I would personally put those points in something like Eye for an Eye or vindication.

Two Handed Weapon Specialization.
Description:
Increases the damage you deal with two handed weapons by a percentage.
Ranks:
Rank 1- Damage increase of 2%.
Rank 2- Damage increase of 4%.
Rank 3- Damage increase of 6%.
Usefulness:

Commentary:
If you want to DPS you will need to use a two hander, so this is perfect for increasing your damage. I would highly recommend it.

Sanctity Aura
Description:
Increases Holy damage done by all party members by 10%
Ranks:
One Rank
Usefulness:

Commentary:
Those who rely on Holy damage from seals and judgments should really have this up. The downside is that it will only really benefit you or other paladins in your group. In PVP it is awesome, especially if you specialize in magic damage over physical damage. But in PVE it is only really useful for solo activities. If you put points in the improved version you'll get even more out of it though.

Improved Sanctity Aura.
Description:
The amount of damage done by targets affected by Sanctity Aura is increased.
Ranks:
Rank one- 1% extra damage.
Rank two- 2% extra damage.
Usefulness:

Commentary:

The primary purpose of this talent is to give retribution speced paladins a more useful spot in a group environment. The overall damage increase lets you use SA more often in groups where before it was just useless. Even with this buff though you probably won't see it in groups because other auras have better effects. It's true power would be when grouping with other paladins for small group work or for leveling. But in a raid or instance stick with your more balanced auras.

Vengeance
Description:
Gives you a bonus to Physical and Holy damage for 15 seconds after dealing a critical strike from a weapon strike, spell or ability. Can stack up to three times.
Ranks:
Rank 1- 1% damage increase.
Rank 2- 2% damage increase.
Rank 3- 3% damage increase.
Rank 4- 4% damage increase.
Rank 5- 5% damage increase.
Usefulness:

Commentary:
After making such a huge investment in such a focused tree its nice to see a big payout like this. Many paladins spec Retribution just for this and then focus on increasing their critical strike gear. If it is available to you definitely get it.

Sanctified Judgement
Description:
Gives your Judgment spell a chance of returning 50% of its mana cost.
Ranks:
Rank one- 33% chance
Rank two- 66% chance
Rank three- 100%
Usefulness:

Commentary:
Those who spec to cause damage will rarely have a great deal of mana. This gives you much more mana efficiency, but it is only useful if you like to judge every eight seconds. At this point you also have access to Vengeance which is a better talent in my opinion.

Sanctified Seals
Description:
Increases your chance to critically hit with all spells and attacks and reduces the chance your seals will be dispelled.
Ranks:
Rank one- 1%
Rank two- 2%
Rank three- 3%
Usefulness:

Commentary:
The main point of this talent is the increase to critical strike. This alone is worth three points. But the dispel resistance is not very useful. The only place you might have your seals dispelled is in PVP, but even then it doesn't seem like that big of a problem.

Repentance
Name:
Repentance
Description:
Incapacitates the target for six seconds. Any damage caused will awaken them and works only on humanoids.
Ranks:
One rank
Usefulness:

Commentary:
This is one of the best crowd controls in the game, especially since it is an instant cast. In PVP where everyone is a humanoid it can be used to escape a pursuing enemy, give you six seconds to heal yourself to full health and it also increases the damage you deal with Judgment of Command. If you have gone all the way up to Vengeance you should strongly consider getting this.

Divine Purpose
Description:
Melee and ranged critical strikes against you cause less damage.
Ranks:
Rank one- 4% less damage.
Rank two- 7% less damage.
Rank three- 10% less damage.
Usefulness:

Commentary:
This is designed to give you more survivability, but it’s really not that great right now. It is primarily designed to work with the Resilience system in PVP but at this point you should already have enough points to get to the next tier so I would avoid this.

Fanaticism
Description:
Increases the critical strike chance of all Judgments capable of a critical hit by a percentage and reduces threat..
Ranks:
Rank one- 3% increased crit, 6% decreased threat.
Rank two- 6% increased crit, 12% decreased threat.
Rank three- 9% increased crit, 18% decreased threat.
Rank four- 12% increased crit, 24% decreased threat.
Rank five- 15% increased crit, 30% decreased threat..
Usefulness:

Commentary:
This is designed to work together with Crusader Strike to cause large amounts of holy damage. Since it is added on to your existing critical strike chance your damage output will rise dramatically. Definitely get this if you want to maximize your damage. The decrease in threat is also vital since a paladin has no other innate threat reducing moves like a rogue or hunter.

Crusader Strike
Name:
Crusader Strike
Description:
An instant strike that causes 110% weapon damage as holy damage and refreshes all judgments on the target.
Ranks:
One rank.
Usefulness:

Commentary:

This is an incredible ability. It gives us an extra powered up attack every six seconds which works well with our other abilities like Seal of Command or Hammer of Justice. The boost is only a minor addition though. Its real strength is the way it can give you an extra attack. The ability to refresh your judgments is another great bonus designed to make ret specced paladins more viable in raids. Since it deals holy damage it can also help you with threat if you are off tanking in a group as well.