You have a +1 bonus to attack and damage rolls made with this weapon.
When you roll a 20 with this magic weapon, the target takes an extra 7 Bludgeoning damage.
Note: According to the SRD, it is an extra 2d6 Bludgeoning damage, although this is incorrect.
If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.