One handed Weapon Master

You've learned to how to target the weak spots in your enemies armor with precision and finesse, letting its precision empower your strikes. You gain the following benefits:

• On your turn, when you score a critical hit with a melee weapon you cripple the target. You lower there AC by 4 for 1 minute.
• Before you make a melee attack with a one handed melee weapon that you are proficient with, you can choose to take a -3 penalty to the attack roll. If the attack hits, you add +5 to the attack's damage.