Twinspawn Maulhammer

Weapon (maul & warhammer), rare (requires attunement) Made of the fossilised remains of an old one’s spawn, the holes within this double-headed maul sparkle with illusory motes of light. As a bonus action, you can separate this maul into two warhammers. Both maul and warhammers have a +1 bonus to attack and damage rolls made with them. You can spend a bonus action to convert them back into a maul.
  Duplicate. As part of the bonus action to separate the warhammers (or as a bonus action when they’re already separated), you can create an illusory double of yourself that carries one of the warhammers for 1 minute. As part of the bonus action to create it, and as bonus action on each of your turns, you can move the duplicate up to 20 feet to a point you can see and make a melee weapon attack against a target within 5 feet of the duplicate. Use your Charisma modifier for attack and damage rolls made in this way.
  The duplicate can’t be harmed, though it can be dispelled by a dispel magic spell or similar magic. A creature that succeeds on a DC 15 Wisdom (Perception) check or that physically interacts with the duplicate perceives that it is illusory and that the weapon is floating. Once you have used this property, you can’t do so again until the following dawn.