Has anyone ever suggested this before? Some sort of straight equation, like, -1% attack speed/run speed/damage per HP damage you receive. It would change the game drastically, which I'm sure a lot of people wouldn't care for, but it would clear up a lot of the debates about stagger and stuff - none of those secondary weapon effects would be needed, as this one mechanic would account for it all.
Simply getting damaged would make you, for the remainder of that round (in battle, or life in siege), less effective. It's more realistic than the current model where you aren't hindered until you're dead, it further rewards blocking skills, allows two equal players to wear each other down (avoiding never-ending block-trading), and makes armor even more valuable (again, like in real life).
Just a thought. It would surely make the game more frustrating (for those who find games frustrating), but it could also lead to some epic last-stand moments when you're clinging on to life by a thread, and still manage to fight your way free.