While I didn’t love Star Wars Saga Edition for a lot of reasons, I did love the condition track. I like the idea of being able to subdue an enemy instead of mercilessly beat the down. Also, in a lot of RPGs, the “More then None, Ready to Run!” attitude is a bit to pervasive. I want a slightly more realistic approach to combat. To that end, I present the condition track.
Basically, as you lose hit points, your condition gets worse. For every quarter of your HP total you lose, you gain a -1 wound penalty to all actions and saves. This represents you physically becoming less able to do anything as you become more and more broken. When you are healed up past a quarter mark, you lose the would penalties associated with being that wounded. When you have a -4 penalty, you pass out. While this would normally be you’ve lost all your hit points, spells could easily fit in this space that allow you to impose conditions on enemies like a stunning blast. To be kind to both the GM and players, I think the saving throws you make when a character has less then 0 HP should not have the wound penalty as this would kill players far to often.
When you lose constitution points from say a wight, you would track your current hit points relative to your previous maximum, not your new maximum. This way a wight will leach away your life just like any other creature.
I would also suggest when you take damage equal to double your constitution score, you have to make a constitution saving throw DC= Challenge rating of the creature that damaged you.