Give us a TRAINING MONTAGE for Kinu....okay, I exaggerate a little...but, we could have the option to train Kinu and teach her one or two skills/abilities for her questline, or give her advice. So for example, she could be given Rend, Fan of Blades, or dischord, skills like that.
Alternatively, we could teach her to prepare for a fight or something, and depending on the advice we give, she could start the fight with like...2x Leanstones, 2 extra vulneraries, or defence/offense buffing items.
Final idea for something along these lines would have it the other way round: let Kinu fight the champion in a sparring battle, but you control Kinu instead. We've established that the champ can more or less master the basics of a weapon/fighting style in an incredibly short period of time, with enough information from Kinu, they could serve as a crude imitation of Raphael, or at least mimic his swordplay, to let Kinu train against his fighting style. There's a large difference between practicing moves and being able to execute them against an opponent that wants you dead, after all.
This last method wouldn't give her any inherent upsides or downsidess in her questline, but it would be a really cool thing to do for her.