Ok
If you approved then that is different
But, throwing a rock was different, since there was a skill activated, <<Blade Throwing>> or other names it goes by
It required the pre-motion before throwing

Also hitting without skill activation works, but it has very little effect/damage
This was the problem many beginners had when starting SAO

Anyway, with the shields, you probably could parry, but I am unsure about any attacks with significant damage. Maybe stun type abilities and slowing them with bashes or something.