Amputator has no redeeming qualities over Acheron. It just does less damage, but can attack Undead and Fiends. You could just get a elemental brandish for undead and fiends. Amputator should do Sleep Status because well it's a medical weapon based off of amputation. When you Amputate a limb in a hospital, the patient is usually given drugs to prevent blood loss, ease the pain, or to put them to sleep. Giving this weapon a Strong Sleep Status would really fit with the theme. It would also be the only weapon in the game that does Strong Sleep. The only thing you would have to program is how strong the sleep status actually is. It shouldn't be much work to just add a status to an already existing weapon to make it viable.