Ye, 25 then. My balancing is outta whack.

I’d say that her Parry mechanic is sorta like a repelling ward around her Instrument? When attacks strike it, rather than striking the surface of the blade or scabbard, it hits the ward instead, redirecting the incoming attack. In general, the type of repulsion would be…

If ranged projectile attack, deflect like basically any anime swordsman deflecting bullets.

If fluid or channeled attack, split in half like the Red Sea while remaining dry.

If melee attack, reflect and send them reeling back from Newton’s law of motion, as if they were a bouncy ball that just hit a hard wall.

So for ball of mucus, it’d split around her, the acid having not actually touched her Instrument, while if it was a fireball set to explode on impact, it’d be deflected away and explode after it strikes the ground, rather than when it struck the sword.