Hmm... I have to say I like the idea of an LWC break-in skill, but I'd try to limit it some more than that. Again, don't know if this would be practical, but instead of outright unlocking the chest maybe it could allow you to pick 1-3ish things out and remove them from the chest within so much time, say 30 seconds, and the window closes and you have to succeed with lockpick again to get more. Perhaps also give a subtle little message in chat, simply a "click!" will do.
A pickpocket ability with many of the same sort of restrictions would be good as well, you rightclick the person, and after your thievery time limit is up it gives a little message. "Is it just me, or are your pockets...lighter?"For people there wouldn't need to be a hard limit for items, because they can respond to the situation in a timely manner, namely by attacking or by Ging the F O.
Also, giving thieves the ability to check the chest for traps before opening it. Rightclick with a bound item, and it gives a message denoting whether or not it'll be safe to open.