Previously, she wouldn't have had the strength to keep Ethan in check for even a second. She was still just barely on par with him now, but added on with the momentary surprise and the sudden break from her previous pattern gave Ethan enough of a shock that she was able to do this one reckless move. Also with her new harder scales, that headbutt would definitely hurt more than a mere Rank 2 Mortal Stage headbutt.
