The only trouble with that is that orc young and berserkers can stun automatically, without even doing any damage.
They stun only if they ‘hit‘ with their charge skill, but if it’s a ‘miss‘, then no stun applies. So it’s ok as it is – good base defence or shieldwall and you’re safe.
If we assume the stun here is like being disoriented or just breaking a posture enough to drop riposte/shield/spearwall, then the mercenary still can hear and see what happened around him, so morale check should work as usual.
