Corsets give more movement than most people seems to think, but yeah, would never fight or dance in a proper full boned corset.

Corset flexibility depends on two things 1. Boning 2. Material. Corsets can be made with more or less boning which in turn can be more or less flexible. Less boning/flexible boning=more movement. Still wouldn't ware one in a fight by choice. Especially not with that neck strap(if its for anything other than show then it is also restricting blood flow to the brain)

That being said it's likely to be a bodice rather than a corset. Bodice are outerwear and usually lack bones, as such they usually offer much more flexibility. Hers appears to be made of leather though which, if thick enough to be considered armor, is going to f that potential flexibility right up. Also, leather dosent breath at all so sweat city.

Also, who gives a f? It's a game. Whatever makes you happy is good enough.

TL;DR IRL a corset in battle is stupid af. In game wear whatever makes u happy.