[quote=@Vortex]
Its not. But as I said before I wrote the character not really thinking about the fatc that hes OP, so im at a loss on how to make him weak.
[/quote]

Well, you can still be a very talented destruction/spell slinging focused mage. Potential is different than actual power, and it would be hard for a wandering wizard to have access to the same information he would have in a solid learning environment, and one of the best at that. The GM seems to not want "The absolute top class of mage in Tamriel", but they're fine with talented. 

You could always say that events happened nearly the same. Your character was talented and growing as a student of magick and showed great promise and abilities, and one day could've been great. But they started to dabble in forbidden arts and got kicked out because of that. Logically speaking, no matter your talent, without a teacher to teach you and other such resources(such as books, records, and artifacts), you will be limited in your capability to grow and learn as a mage. In that sense, he has been held back from reaching his potential due to not having good resources and a whole academy backing his research, just what he can afford to get on the road(And what little resources a court would give him).

 He isn't the strongest in Tamriel at the start of the RP, but can slowly fulfill his very high potential over time.