Why does it need damage?
It should just be better at what it's meant to do, mitigate.

Maybe higher returns and more consistency. I think it'd be better flipped.
Parry stat should give you more damage reduction from parrying, while parrying should have a set percent that's reasonably high.

It could also even just be that you always parry, and how much you parry depends on the stat.
That could be balanced.

Damage added it could be an option, but that shouldn't be the main reason to get it.
It should be attractive for its mitigation. And your survival should be in danger if you ignore it.