You can use a bonus action to cause thick, black oil to coat the blade. The oil remains for 1 minute or until an attack using this weapon hits a creature. That creature must succeed on a DC 13 Constitution saving throw or become grappled for 1 minute as webs spew out of the wound and attach the creature to the ground, making them unable to move. In order to break free, the creature must succeed on a DC 12 Strength saving throw.