I'm working on a story with a type of magic where works much like granting fiefs. You must study and practice to use it, but basically, you get the raw ability by recieving a grant of magic from a superior. Kings might hand it down to their vassals, gods to their priests, spirits to whoever they take a liking to. It is handed down in the form of a specific amount you can channel at once, and when you hand a sub-channel down, it is lost to you unless you retrieve it through a complicated ceremony. There are differents types of and uses for magic, but I won't go into those. Mainly, I'm interested in what similar things have been done before, and what holes I may have in the concept.