Which refine on Caeda?

Personal definitely. Flashing Blade on a flier is everything, especially considering no other fliers other than her and Clair can use it. She'll be dishing out Iceberg bombs all day.
Also, if I may, your Caeda vastly needs improvement. From the looks of it, she's decent already, but you can make her even better. Here's mine to give a good basis on what you could do with her. But she could run a lot of different things like Fury, Waves, Breakers, Bonds, Push, all sorts of things. Be creative!

I suggest her personal but with moonbow as special instead. When in desperation range you will be able to kill all green/red armors and cavs, even most blue. If you dont plan on killing blue with her you can use glimmer