Thief help
Dungeons are going to require toughness, you cannot do them unless you can survive the insane amounts of damage the monsters do there.
PvP is very different, D/D backstab, Pistol Whip burst, that new S/D daze thingy that was just posted are, have been or look viable.
While Questing I’d honestly keep with P/D and get S/P as well. Signet of Malice+Pistol Whip keeps me alive in Orr so it should keep you alive while questing.