Why Can't you use Grips when using H2H?

[Zyeriis]

Players can do that too if they leave their main hand empty and equip a shield offhand. You can't use H2H WS if you do this however.

That doesn't count as equipping a h2h weapon in one hand. That's just one fist as a weapon.

Anyway my post was more to show that h2h can't use grips because they're 2 individual weapons that get dual wielded but in a single slot (the main one).