Backbiter

The weapon you indicate during the spell's casting briefly shimmers with a black aura that disappears in an eyeblink.

When you cast this spell, choose one melee weapon within range. The next time a creature uses this weapon to make a melee attack, they have advantage on their attack roll and then the weapon turns on its wielder, provided the spell hasn't ended. The next attack afterward that hits a creature deals damage to the weapon's wielder instead of their target, in addition to the weapon's typical effects. This damage cannot be made non-lethal.

As an action, a creature can attempt an investigation check against your spell save DC when closely analyzing the weapon to find that it was tampered with. As an action, a creature can make an arcana check against your spell save DC to disarm the weapon and end this spell.

Once the weapon attacks its wielder, regardless of whether the attack hits or misses, the spell ends.

At Higher Levels: When you cast this spell using a spell slot of 3rd or 4th level, this spell lasts up to 8 hours. When you use a spell slot of 5th or 6th level, this spell lasts up to 24 hours. When you use a spell slot of 7th level or higher, this spell lasts until dispelled.