I am amused by how Negi has become the shonen equivalent of Batman, capable of beating most anything given enough time to come up with new countermeasures.
What is it that you fight for? Look at Kotarou-kun. He truly enjoys the battle. Why do you fight? For your friends? Trivial. Utterly insignificant. Negi-kun, you dissapointment me. The reason a man fights is his alone, and always will be. That is how it must be. "Anger". "Hate". "Revenge". Those are especially good reasons. Anyone can put their whole soul into fighting for those. Or, for a slightly more wholesome reason, you could fight for "the joy of becoming stronger". Without a reason, there is no pleasure in fighting.
I-I've never fought for pleasure... I fight
Because you feel responsible for getting innocent, non-magical girls involved? Out of a sense of obligation to save them? A sense of duty may spur you on, but it will never make you fight in real earnest. Truly disappointing. Or...perhaps...you fight to escape your memories of that snowy night?
Herrman and Negi.
Unless they can obtain infinite wisdom as well as infinite strength, those who seek power will most certainly hit a wall. And when they reach that point, all people, without exception, will witness their own weakness. Strength that can't face its own weakness is no better than paper-mache. Merely playing at contests of might is the same as children fighting over who is taller.
Please don't think of yourself as a supporting character. We're all leading characters.