Another interesting mechanic would be different types of attacks: thrust, slash left, slash right, slash down. The player can see the attack beginning and has a small amount of time to choose the correct defense to that attack. Choosing the correct defense reduces the amount of focus lost. You could also add shields. If you press block with a shield it'll block any attack with minimal loss of focus. Shields would have hit points and break if used too many times.
Mount and Blade is the closest game I've played to this. It still has hit points, but that makes sense for a medieval game where you're fighting heavily armored humans.
The only difference I can tell is the game uses the term "poise" instead of "focus." But the notion of attack variants, responses and improvised gear pretty closely meshes with what everybody here and at the original post's thread seem to want.
Mount and Blade is the closest game I've played to this. It still has hit points, but that makes sense for a medieval game where you're fighting heavily armored humans.