You are missing a hand or most of your arm.
Effect: You cannot wield two weapons at the same time, two handed weapons, or a shield in your off hand, but you can use your stump to defend yourself from combat maneuvers, gaining a +2 to your CMD.
At 5th level, you can use your stump as a natural weapon. You can make a slam attack that deals 1d6 damage plus your full Strength modifier.
At 10th level, the bonus to your CMD increases to +4.
At 15th level, the damage from your slam attack increases to 1d8.