Now, first, what exactly does this mean? Dedicated, as in, you are the owner, and you will it? (eg: make it go to you, make it change possixrs etc. like others do).
Second, correct me if I'm wrong, but aren't Deadric artefacts made from the blood of deadra princes? Or atleast, don't they represent a portion of their princes? If so where the hell is the "soul" of your staff from? In game it basicly says two things:
1. The power comes from madness of manic and demented into the pools and through that into your staff. This makes sense in itself, you are the madgod your power stems from madness. But..
2. Deadric artefacts are parts of Deadric Princes and..
3. You staff IS a deadric artefact (well.. reportedly )
If #3 wasn't true, it'd all make perfect sense. But if #3 IS true, then it implies somewhat indirectly that either Sheogorath isn't completly Jyggylag, and you draw the deadric aspect from Him, or that you are Him, but then, Jyggy must've lost something
Because if #3 and #2 then some Deadra must've given the power
This isn't exactly "is the PC a deadra" question. We can't answer that. I'm just trying to find out where all the power comes from. Remember, we're in Oblivion, near the void, creation doesn't exactly go here much.