Shrapnel

Magical sword, perhaps?

I have been cooking a setting more or less like that, nowadays. Futuristic, space exploration, stuff. Almost no aliens and almost no magic. But the aliens I have are heavily committed to the vampire theme, and cannot be hurt, almost. Only think humans have access to that can hurt them is magical weapons.

One can put magic in bullets, but it is not compatible with industrial production. Therefore, is usually not a viable investment. Magical blades cut better than normal blades, last longer. And unlike bullets can be used many times. Given that context, would make sense for a character in an armour like that to carry a sword. Since that is likely the only weapon she can get that makes more than slow down momentarily vampires and shadows.