Anyone here familiar with the SCA (Society for Creative Anachronism) and their system of light fighting? Recent discussions here have reminded me of it due to the fact that it contains both free-sparring and theatrical elements. Valid targets are basically the whole body.
A blow to either arm robs the contestant of use of that arm.
A blow to the other arm after one has already been hit ends the match. (Can't very well fight with a sword without any arms to wield it.)
A blow to either leg, and the contestant fights the rest of the match on his or her knees. (Which can actually make them quite dangerous.)
A blow to the torso or the head ends the match.
Fighters go at it until one of them is "dead". Meaningless cool points often go to one that "dies" gracefully, (ie. Doubling over and slowly collapsing as if actually having been run-through.)
It is free-sparring rather than point sparring, so the match continues without interruption inbetween hits.
Thoughts?

Very familiar with SCA. My younger sister is a fencer (learning and instructing), and frequently does SCA battles, when she isn't playing music with period instruments. In fact, her glory was sung at a recent feast, and she was awarded for a 'celebrated kill'.

The SCA fighting can be much more free-form (I've seen/heard of people using all mixed weapons, from staffs and clubs and swords and spears, to maces, halberds, you-name-it). However, the scoring system is fairly unrealistic. Regular SCA combatants will practice fighting on their knees, or one-armed, to be able to compete according to the rules you've described. Some fighters are even known for their ferocity on their knees, and other fighters will avoid leg shots to make sure they don't have to face them in a kneeling position. This of course is very unrealistic, since I don't know, historically, of any one-armed or one-legged fighters who then vanquished their battlefield opponent.

Like any sparring system, it can only approximate sword fighting, and it must be limited for safety and scoring reasons.

I have done some SCA fighting both light and heavy (never enough time to get really into it). The last demo my students did in May was choreographed with "wounds" SCA style (my daughter and one of my students also SCA). The only thing I would add would be a "time limit" on being wounded due to the effects of blood loss and shock.

"It's only a flesh wound..." -The Black Knight, Monty Python and the Holy Grail

Yeah I'm not an SCA type myself, and I've never been to any of their events. (They kind of scare me, actually. I prefer Renn Faires, where people acknowledge that it's just pretend.) An old friend of mine is a pretty hard-core member, though. She introduced me to this system, and I actually like it. Among my limited group of peers, at least, we've had more success with this than when I try to bring in rules from my kendo experience.

This is the one that set off a red flag for me. After suffering a wound to the quadricept or hamstring, kneeling is the last thing a person would do. Realistically, kneeling after taking such a blow would actually open the wound even more, causing blinding pain. Wouldn't it make more sense to have the fighter stand on one leg after being hit?

I wonder how those who like sparring would react to an electronic punishment system. We already have workable systems that can record hits of a pre-determined intensity as a point. I wonder what sort of response a company that produced gear which would cripple specific muscle groups with pain on any "legal" hit would get...

Hit to the leg? Fighter's leg spasms and down they go...

Ouuuuch! Think about cuts to the head. . . However, my daughter would love this system , I will NEVER let her spar with her little sister!