Civil ability points are rare. Each point in Thievery increases the amount of weight or costs you can steal, for example the first point is up to 300 Gold, the second up to 450 Gold. So I would advice to dedicate one char to Thievery. I find Thievery on more chars (you can only steal once per NPC and party member) a bit cheaty, as stealing is really powerful and low (no) risk.