So, I just read the third edition of Unknown Armies and I'm a huge fan of what they did with the system.

Basically, you have five scales in the game, each of which represents a kind of trauma. These are your character stats: Helplessness, Isolation, Self, Unnaturalness and Violence. In each of these categories, you can be hardened, damaged or both. Hardened characters become immune to trauma on that scale, but it also comes with disadvantages. Hardening also changes your skills: more hardened characters automatically are lower in some skills, but higher in others. For example, as you become more hardened to unnatural events, your Notice skill goes down, but your Lying skill goes up.

They also give you a general guide on how your character might behave, of course. For example, a character who is hardened to Isolation doesn't care about other people. A character who is damaged in any of the categories is probably fearful.