What is Kill la Kill being, uh... crossed over with? Satsuki's "armor" or whatever it is looks vaguely familiar, but I can't remember where it comes from.
Technically this is a Star wars cosplay, not a crossover.
In the artists verse they were at a Con of some sort.
Satsuki is Princess Leia
Ryuuko is Han Solo.
No, but you're still pretty obvious. Luckily (or unluckily, depending on your perspective) this is Lucina we're talking about.
Incidentally, this is from a scene from a Lucina x Severa fanfiction called Secret Dreamer in case anyone is interested. There's more info at the source.