In the rules, you never decrease your body rating for damage soak rolls in Shadowrun 5e. Let’s play with that…
Glass Jaw
Bonus: 7, 15, or 25 karma
You might be awesome in a fight, but when you get hit, it hurts! For seven karma, when you have three boxes of physical or stun damage, you take a minus -1 penalty to all damage soak rolls. For 15 karma, when you have two full tracks of physical, stun, or a combination of both, you take a -2 penalty. For 25 karma, when you have three filled tracks of physical, stun, or a combination of both, you take a -3 penalty to all damage soak rolls.
Thoughts?
Throat Punch Games 