Combat Dagger

Combat Dagger is a talent build that developed from a need to move away from the flat damage of Eviscerate. Better weapons have changed the focus in PvE from burst damage popular earlier in the game to maintaining a high sustained damage. Toward this end, this build emphasizes the high damage possible from Backstab and increasing damage from normal swings by increasing attack speed with the finisher Slice and Dice.

A typical build is known at 16/25/10 and could be built as such -

Assassination - 16 points

5/5 Malice

5% crit is never a bad thing.

3/3 Ruthlessness

Useful in its own right for maintaining Slice and Dice as long as possible, and a prereq for Relentless Strikes

2/3 Improved Slice and Dice

An important talent for improving overall DPS. A possible variation is to move one point from Dagger Specialization to get 3/3 Improved Slice and Dice. This extends a 5 point Slice and Dice to 30 seconds of hasted attack speed, allowing you to backstab 5 more times and get another full 5 point Slice and Dice, even if Relentless Strikes does not trigger.

1/1 Relentless Strikes

Very useful for keeping momentum up. Slice and Dice becomes essentially free, with your odds increasing as you rack up more CP

5/5 Lethality

Backstab is going to crit, this makes it hurt more. Also, you can wow and amaze your friends and foes by backstabbing for more than a critical Eviscerate :P

Combat - 25 points

2/2 Improved Sinister Strike

Every so often, it's nice to use a nonpositional attack to rack up some CP as you find position. Moving these points to Lightning Reflexes is not terrible either.

3/3 Improved Gouge

Sneaking a bit of utility in. In PvP or duels, Improved Gouge can buy you time to run and restealth. In PvE, you can run unimpeded for a bit if you get a sticky situation. As with Improved Sinister Strikes, these points could be spent in Lighting Reflexes as well.

3/3 Improved Backstab

Another key talent. Coupled with your rogue's natural crit rate, Improved Backstab should make non-crit Backstabs so rare as to be a thing of legend.

5/5 Precision

Increasing your chance to hit is a straight increase to your damage, and only gets better as you get better gear. With patch 1.8, the cap on +hit was removed, so it is possible to reduce the dual wield miss rate to zero if desired. Here, we're interested because of the damage increase and because this is a prerequisite to Dual Wield Specialization.

2/5 Deflection

Filler points basically, and Parry is better than Dodge.

5/5 Dual Wield Specialization

A talent that has no equivilent from equipment. Arguably stronger than Dagger Specialization, since you can get more crit from better equipment.

4/5 Dagger Specialization

More crit is never bad.

1/1 Blade Flurry

A great ability for PvE and PvP by allowing your attacks to hit the closest adjacent target. It is recommended that you activate Slice and Dice before turning on Blade Flurry to enhance your damage even further. One tip from Quark is to target the lighest armor enemy since Blade Flurry was returned to its flat damage with patch 1.9. Since Blade Flurry damage is not reduced by armor, hit the lightest armored foe (say a mage), and watch your damage against high armored foes increase by large percentage.

Subtlety - 10 points

5/5 Master of Deception

These are filler points for getting to Opportunity. Feel free to use them in Camouflage or Rapid Concealment as your heart desires.

5/5 Opportunity

Another damage booster for your main special attack. Part of building a better backstab.

Playstyle

The general idea is to open with Ambush or Cheapshot, depending on your situation (Cheapshot is generally discouraged when your tank is a warrior, although all tanks may get irritated when the mob they are trying to reposition is suddenly taking a nap; Ambush can cause too much aggro early on, Garrote isn't all that impressive) and then convert that Combo Point(s) into Slice and Dice for immediate haste. After that, get position in the rear arc, settle in to start Backstabbing and let the damage fly. Slice and Dice as necessary to keep your haste up through the fight. Eviscerate is mostly for those cases when it will finish the last mob of a pull off or you just refreshed Slice and Dice and you cannot get a bigger S&D off before the mob dies.

In regards to gaining aggro, take Blessing of Salvation, Greater Blessing of Salvation, or Tranquil Air Totem coverage as possible.

After that, there are two schools of thought of aggro management.

- First, Feint as necessary to stay below the tank. This results in less energy for Backstabbing, but it keeps Vanish in reserve for when things go wrong.

- Second, accept the fact that a high DPS rogue will gain aggro from doing what they do best, regardless of what the tank does, and use Vanish as a reset. A successful Vanish will remove the rogue from the mob's aggro list, allowing the rogue to perform another Opener and build aggro up to the tank again. 

I lean towards the first school of thought, because I'm a cheap bastard and reagents cost money. I can accept doing less damage than the other rogue if I take less damage and help the raid move more smoothly.