Think about your thieves. There are all manner of specialists: pick pockets, second story men, jewel thieves. They know their stuff. Jewel thieves need to know how to appraise gems and jewelry so they will choose the best stuff, and not get fooled by forgeries and paste. But how far does it go?
Are there fantasy era specialists? There should be. In the same vein that a jewel thief must know the good stuff from the fakes, a magic thief will need to be able to understand the real magic from the stage theatrics. But is specializing in magic enough? Wouldn’t there need to be different styles of specialist for stealing alchemicals? A separate specialist for acquiring components and other materials? What about someone who goes after the enchantments themselves? Even the necromancers would need someone who knew how to get the right things for them. After all, it would be incredibly embarrassing to send a thief after an important skull, only to have him steal the wrong one. (“Abby someone.”) In a similar fashion a mentalist in need of the proper psychometric items would need someone who understood which items held the proper mental vestiges.
These thieving specialists need to understand their targets, which means they probably need to have some skill in them. That means they might know a bit of alchemy in order to understand both the alchemical products and equipment. Or they may need training in magic in order to read spell books and mystic scrolls, in order to know what they are stealing. At the same time, sorcerers would use different styles of traps and tricks then enchanters or alchemists would, so once again, understanding your target(s) will benefit you, and knowing how to handle those types of items and magic would give you a significant advantage. The same should be said for their tools of the trade. Knowing how to beat a sorcerer’s traps does not necessarily position you to get past a necromancer’s.
Honestly, this subject is too huge to do justice in a blog post, but I hope I set your mind spinning. Need some ideas on what a magic thief would be stealing? Check out Alchemist’s Lab for all sorts of fun products and equipment!