Continuing on from the previous post, here's the more "revolutionary" part. In addition to vitality and wounds there is a parallel set of statistics that reflect your ability to handle mental damage/trauma- how easily your character loses their nerve. It's going to take some careful thought, but my hope is to have these stats be just as important as the ones reflecting physical well-being; if I want to do a roleplay system that isn't fundamentally built around physical combat, I'll have to put the same emphasis on other aspects of the system that combat receives. The idea is that every character will have a sort of social "mind games" attack the same way that they have a physical attack. When you face five men, and cut down the first to move at you with a single brutal strike, causing the other four hesitate and draw back- *that* is what I want this system to handle, smoothly and abstractly.
To nail down the basics, just as your Brawn score gives you wound points representing your ability to handle serious physical injury, your Spirit score gives you trauma points representing your ability to handle serious mental damage. And as your class and Endurance scores provide vitality points to negate physical attacks, so does your class and Wits score provide you with the ability to cope with and shrug off things that would leave a weaker-willed man broken and crying.
You also have a mental defense score along with your physical one, which in this system are referred to as your Will Defense (Intellect) and Guard Defense (grace) respectively. It's like a will save with broader applications.
As for the effects of losing your nerve- this means losing all your acuity points, and perhaps becoming shaken. I suspect much of this will still be a function of intimidate and other social skills, but it's still all theoretical. I'd like to hear what thoughts you have with regards to expanded social mechanics- stuff that works within the framework of the d20 system and isn't too complex while still being intuitive and useful.
And no, this isn't the sanity system- losing trauma points isn't normally going to make someone a gibbering maniac. It's just an expansion on mechanics like frightful presence, intimidation, and so on. And it works well within the existing system- a DM can plan to include an in-game scare tactic in the same way he include a pit trap, counting a traumatizing scene as a challenge with a corresponding CR.