Is no. Absolutely not. You cannot steal powers from anyone.
Yes, I know you want to, and I know it's what warlocks generally tend to do, but I have decided that stealing powers from another ACW member is not allowed. Or anybody else for that matter. Those who were around for the last ACW (II) would remember there was far too much of it going on.
It's just confusing, and I the Powers had to intervene. Which sucked, because I'm lazy.
The only way you can get new powers is by winning them or having the Elders, The Source or The Powers granting them to you.
Now. Any questions?