S/D thief is pretty amazing if you get practice with it. The sword 1 hits harder than any other weapon which is great for burst. 2 is great to jump in from ranged, keep Shadow return up to pop back out as soon as you get targeted down. 4 is almost overpowered right now for dagger, especially when you have 2 targets available. This can be 2 players or a ranger and his pet. Hell, I even use critters to bounce off of when I see they are close. It cripples and destroys with its damage. Its so good, I even use it vs. single targets from ranged. Soften them up, then pop in with 2 to immob them, and tear them apart. 5 is not as useful, but if you need to make a quick escape or in 2v1, 2v2 you need to get untarget, its a strong way to stealth and then daze back in with your stealth sword auto. I love S/D and I almost always keep it equipped, and use P/P or P/D as my ranged equip.
You just have to know how to pick your fights, you won’t be able to take damage at all since you’ll want to be specced power/prec. 1 on1 though, any class will be hard pressed to out dps you.