This looks like this is a Hemorrhage build, meaning you'll be using a slow MH weapon for maximal Hemo damage, and a fast OH weapon for poison procs (same weapon setup as a SS-based build). Therefore, I'd suggest dropping any of the dagger-related talents, and making a few other adjustments.
http://db.vanillagaming.org/?talent#fheoRxzZhZxMe0chRoAssassination:
- Even without Shiv, there's little utility to having Improved Poisons. You will typically PvP with dual crippling poison, with occasional mind-numbing poison OH/crippling MH given the situation--but 95% of the time will be dual crippling. The added value to +10% poison proc rate is greatly overshadowed by:
- Improved Expose Armor. This is an excellent talent, and Expose Armor used strategically in PvP (3-point expose on casters, 5-point on mail/plate) can help burst down a flag carrier or allow you to win a one-on-one. Ironically, Expose Armor is more effective on lower-armor targets due to armor mechanics, and if used intelligently can be extremely effective.
Combat:
- Improved Gouge. Don't underestimate the added utility of Improved Gouge. It allows an extra bandage tick, gives you just the amount of time to re-stealth before Gouge breaks, can provide you an extra tick of energy, etc. It's an extremely effective CC PvP ability and is definitely worth the 3-point investment.
Subtlety:
- As previously mentioned, we will move all eight talent points out of Opportunity and Improved Ambush. If an opportunity arises when you need to Ambush, you can weapon swap to a dagger and CB it. If your target is eating/drinking, Ambush will crit 100% of the time, making Improved Ambush useless. However, since you will have 3/3 Initiative and 2/2 Dirty Deeds, Cheap Shot will be your opener 95% of the time.
- Don't worry about Setup. Combo Points will be the least of your worries, with Hemorrhage (the most energy-efficient primary attack CP generator in Vanilla) and 3/3 Initiative & 2/2 Dirty Deeds. These points are better spent elsewhere.
- Elusiveness: This was mentioned by another poster, Elusiveness will help you in any extended combat situation (e.g. battlegrounds). Kind of a throwaway talent, but better than nothing.
- Camouflage: 5/5 Camouflage is a luxury that can only be afforded with a subtlety-heavy spec like this. It's an underrated talent that can allow you to be a CC nightmare with:
- Improved Sap: Since you'll be moving around at 90% speed in stealth with 5/5 Camouflage (or more if you have the right boots), this talent can help you CC someone and still get your CP on another target without needing to Vanish.
- Those two extra points: This is a decision that you can make based on your preference. I'd recommend either Sleight of Hand or Heightened Senses (my preference). Either one provides a marginal benefit, but would be more effective than really any other option.
If you're looking for a Backstab-based build that still has Preparation, the standard here is 21/8/22:
http://db.vanillagaming.org/?talent#fheoRxzZGcZE0sc0hkSome people prefer to move a point out of Murder and Ruthlessness for 2/2 Remorseless Attacks, and that one point in Camouflage could be in Elusiveness. Otherwise, there isn't a whole lot of wiggle room in this one. 2/2 Improved Sinister Strike is included more for stun locking purposes than weapon swapping to a slower weapon to SS a target, but this can be somewhat effective on a stubborn plate opponent.