Yeah, with mc you can kinda understand it, magic medics and what not most likely being valuable and rare, but even then, you'd think she'd be working in the rear and not the front. But the lad just looks way too young to hold a rifle.
I think she's there to protect high-value assets like her captain or that guy with the lighting spear. I imagine that a considerable part of the war is fought between those superhuman-like figures on the frontlines.