I found something called a sigil stone - it adds either 5 frost damage or 10 absorb cold damage if added to a weapon or something you wear. Doesnt look like I need any special magic skills to do it either. It was in one of those spooky Ayelid shrines.

Did anyone read the book you find at Cloud Top? What is it? I was that keen to get in with the Mages Guild I just rushed back to town and handed it over.