I think this skill should not be used against other players, but until now that depends on the player's personal ethics, and since the skill is able to get used there's no way you can avoid this behavior.
So, wouldnt it be a good idea to put it clear if stealing is or isn't allowed in each server?
And if it is allowed, it could be balanced with the pking posibility too.
I might sound as Gollum here

Everybody cares too much about levels, but if you have the items that brought you to a certain level you will sooner or later (and very probably much faster than before) go back to the level you was but you may find it very hard to find some kind of items again in the world.
There are some who think stealing is a way to compete and that "about equal level characters should be allowed to compete because it's a part of the game".
But i don't see it very logical that a server that doesn't allow pk'ing allows stealing.
What do you think?