They look up at the change in tone, of the noise they've almost gotten used to - and then they dart backwards out of the way, sword at the ready, as the disk plummets down.

No parrying, not yet. They want to see their foe, not just their weapon; if they can lure their unseen assailant out, they'll be able to fight better. They stare upwards, from where the disk originated from; attempting to pick out some features amidst the environment's clutter.