Parry doesn't always block everything - this mod will allow you to block only a fixed part of the hit, depending on the type of weapon you both have. For example, if you're using a two-handed sword, then you'll have to partially paste your guard if the hit comes from the other side. The same goes for axes and other two-handed weapons.

By default, nothing should happen if you are not struck by a two-handed weapon, but any significant blow from a two-handed sword should partially penetrate your guard.

This mod works by reducing the "magnitude" of the blow before armor/perk. The code is pretty simple, so it should be compatible with almost everything.

This mod allows you to change the settings of the two-handed weapon bonus, and the amount of the reduction in your guard.