Aqua tenses the moment she sees Baiken charging forward, letting herself fall backwards into a flip in order to dodge the blow – the rapier doesn't seem nearly as sturdy as her Keyblade used to be, so blocking the blow seems like a bad idea. She points the rapier at her opponent, channeling the cold feel of her weak ice spell.

"Glacier!"

Hopefully that will startle the other woman to provide her with an opening to strike.