it makes sense for priests and clerics to be fighting in a medieval fantasy style war because they're the healers. every army needs medic. when you have magic, the medics just turn into straight up healers, which are classically priests and clerics.
if you're trying to say that "priests and clerics are only acceptable canonically as healers because of the history of the genre!" well, you're right. but in most militaries, even historically, you had your chaplains, et al, so there's a place for that type of personnel even in real world context.
and that maid looks pretty jarring, aesthetics wise, from what i'm used to seeing as far as fe character designs go. but i don't know what the character design looks like in this game, so maybe it's a bit more modern than i know (or maybe she doesn't look so modern in actual full body pictures?).