[b]1:[/b] So, as you explained, those around her will have an innate power boost compared to ordinary highschool girls, which she is. Her power isn't at a level where she's much stronger than an ordinary girl of her age, since she relies on dire circumstances and consecutive victories to obtain the power others have just be contracting.

[b]2:[/b] That is the point. She will become stronger as time goes on and she obtains more and more glory.

[b]3:[/b] Her power is not useless, if somebody attempts to cheat or lie about the results of a contest or battle, she can prove in an undeniable manner that Mikoto succeeded, thus guaranteeing the boost to Glory, where otherwise she would have failed.