The amount of exp needed to level it up needs to be severely altered, i'm at 50 and it already takes ages. But then again, so does elemental magic, too late in the game obtained and too much exp needed.

Exp gained from the bubble shield also needs to be changed, only by it breaking is horrible, every hit needs to give exp. Combined that it only refreshes existing shields' timer instead of also their health is even more of an oversight.