Rare Weapon (Quarterstaff), Versatile, Requires Attunement 

• You can use this weapon as a spellcasting focus for your warlock spells

Tool of the Witches. Twice per long rest, you can use this item to cast either the Bane spell (1st level) or Hex spell (1st level).
When you hit a creature with an attack made with this weapon, you can immediately cast the spells Bane or Hex as part of the attack action. 

Baleful Bane. When concentrating on the spells Bane or Hex, you can use your bonus action action to end the effect on a single creature within 60 feet that you can see, dealing (1d12 + your proficiency bonus) force damage to them.