That's a decent-looking mechanic! Wording's a little clunky, but par for live. Here's a swing at articulating:
If 'remove Heavy Melee damage' means applying none whatsoever:
Your heavy melee attacks apply to enemies making their own heavy melee attacks no damage but while also preventing their attacks & knocking them back
Or if 'remove Heavy Melee damage' means to only apply light melee damage:
Your heavy melee attacks apply to enemies making their own heavy melee attacks only light melee damage but while also reducing any attacks of theirs to light melee damage & knocking them back
Parry items are underplayed imo so I think reducing the opponent's entirely while only dealing light melee would make for the best version