You gain a +1 bonus to attack and damage rolls made with this magic weapon. When you roll a 20 on an attack roll made with this weapon, the target loses its resistance to bludgeoning, piercing, and slashing damage until the start of your next turn. If it has immunity to bludgeoning, piercing, and slashing damage, its immunity instead becomes resistance to such damage until the start of your next turn. If the creature doesn't have resistance or immunity to such damage, you roll your damage dice three times, instead of twice.