So I've had a look at the AG Zweihander and I've concluded that where the fighting mechanics are concerned it's too dang abstract. The guide's author is right in that the typical AG makes injury just too abstract what with their limited hit points and all that, and his attempt to present a descriptive scheme for wounds is commendable, but it just doesn't work.
So I've decided to have a look at how Mythus handles injury and harm and I've come to the conclusion that it does offer openings for adjustment.
Now in Mythus a Persona will have a Physical Trait ranging from 36 (a real wimp) to 180 (a gnarly dude) points. Injuries can range from just 1 point, to more than 200 depending on circumstances. So I decided to try setting the amount of damage done to a Persona as a ratio of PTrait. Your HP has taken half damage for instance, he functions at half capability. So Bob has a PTrait of 90 and he's taken 44 points of "ouch". 44/90ths factors out to be 22/45ths, and as near as I can figure it means that Bob functions are at 48% of his normal capability. Don't you hate reality?
You can adapt this to your favorite engine, but it could be a fair amount of tinkering. Tinker away.