I've been reading around on the forums about the issues of Steal, Stealth, and Pistol OH are the main things being negatively discussed concerning the thief. Lots of good suggestions are in a lot of these threads concerning these 3 things, but I have not yet to find a noteworthy solution in terms of stealing. The consensus for Stealth is that when traited, it becomes way too strong offensively. And for pistol OH, it just doesn't stack up with dagger OH.
My issue with stealth is that ANet is kind of looking straight forward with its design, and it has a terrible RNG factor that could potentially decide some fights just because you got a crap item. One of the coolest systems I've ever seen in a game with a thief is from Final Fantasy Tactics. You had the choice on a thief whether you wanted to steal gold, armor, item, weapon, or even "heart", which meant if the other character was the opposite sex you could effectively turn them over to your side. I thought it was a genius idea.
For GW2, I think it would be awesome for us to have something like that in place. We don't have lots of weapon choices, and our Steal mechanic as is is pretty lackluster. The Mesmer for instance has their whole setup of building clones and then shattering them. They have a range of selections when it comes to what kind of shatter they want: One that puts up confusion, one with a reflection shield, one that damages and even one that stuns. 4 variations of a mechanic.
Steal could be as follows:
F1 = Steal Weapon Could be either the weapon the player has equipped or a random one as it is now. Just use it to attack, much like how Steal functions now
F2 = Steal Utility Could be a set utility for each class or maybe whichever ones they currently have equipped.
F3 = Steal Boon Self Explanatory. Would work much like Spell Steal does for Mages in WoW. Just steal a random buff that the enemy has on them for yourself. With Traits, this could steal multiple buffs.
The way this system would work is that whenever you use a certain steal, the others will start their cooldown. Steal currently works that only when you USE the item does the CD start. With 3 types, the others could be starting their CD while you choose the best time to use the weapon, utility or boon. You wont be able to use THAT Steal until you use the item, but if you choose to Steal Boon when you have a weapon in your F1 slot, you can do that and then you lose the weapon but gain a boon.
I ultimately think this would be a more active style for Thief and it would make the player choose wisely. Some boons are only active for a few seconds, and some utilities are only good in certain situations. I think the first 2 should be from a specific set of items/utilities because that way it's easier from a design standpoint and also a player's.
Much of what ANet does is extraordinary and innovative. But having Steal be what it is now is pretty bland and uncharacteristic considering how awesome their design team is for this game. We're thieves, let us have a great flexibility when it comes to stealing. Some of us may want that hammer to bash someones face, or that awesome flame turret from that engineer, or a few of us may want to take that Retaliation or Might from the Guardian who just gained it.
I'm open to suggestions for these of course but I honestly feel having multiple variations of steal would be a good way to solve this steal problem. Of course its only beta right now but number tweaking for Steal isn't really what it needs. It needs flavor and I think what I proposed is a good idea for that to happen.