Due to the abyssal corruption, Nine's body had succumbed to an incurable weakness. Unless she drew power from Ansel, she would likely… be confined to a wheelchair for the foreseeable future.
Although the power Ansel could bestow upon Nine was not without cost to himself—whatever he gave her, he would lose—he didn't mind sharing enough to allow her normal mobility. For him, it was a negligible sacrifice. Yet Nine steadfastly refused to accept.
Her words had been: "Even a millionth of your power, Mr.Ansel, would serve a greater purpose if left with you than if given to me."
Only when absolutely necessary would Nine borrow Ansel's power; otherwise, she refused to accept even the slightest amount, deeming it wasteful.
This excessive self-deprecation left Ansel at a loss for words, compelling him to acquiesce to Nine's wishes.