Old injury

Your character has an old injury that still troubles them to this day. Likely a souvenir from a previous battle, it provides an advantage to any attacker who knows to press their against your specific weakness. Whenever an adversary who is aware of the weakness targets the injured area with the Aim / Flourish maneuver, they increase the Vicious quality of their attack by 2 (giving them a +20 to any rolls they make on the Critical Injury Chart) Obviously, GMs should not have the injury be common knowledge, but any d on a physical check could certainly be the old injury acting up again - causing them to suffer pain and take 1 wound and 1 strain.