When killed with weapon in offhand, death message says you were killed by weapon in main hand

If you use a weapon in your offhand to kill someone, you would expect to see a death message saying: "PlayerName was killed by PlayerName with WeaponInOffHand," but instead, it says: "PlayerName was killed by PlayerName with WeaponInMainHand." If you kill the player with your main hand weapon, it displays the same message. Please fix.