You seem to think they're underpowered because you want them to be good at something they aren't intended to be. It's like saying rangers are woefully underpowered because they have too much trouble outside of the wilds, when working in the wilderness is the core class concept in the first place.

Also, are you confused about how steal works or something? Non-pickpockets are good at stealing too.

Unless you're robbing a duo, it would be very hard for anyone but an a-p to knock you out of hiding and then also trap you in combat with them, and even then they'd have to get their iceball about the same pulse you stole on. Even wingsweep takes too long so warriors aren't really a threat unless they have maelstrom.