Kanaboom stick

Weapon (mace), uncommon
  The fact demons are reborn after being killed on them material plane leaves them with a laissez faire attitude towards self-preservation. Taking advantage of their innate resistance to the elements, they can often be found in possession of these crudely enchanted maces that leave a minor path of flaming destruction in their wake. The only limit to this weapon is how much punishment its wielder can suffer.
  As a bonus action you can stick this magic weapon in any open flame or, as an action, you can light the mace as you would a torch. Either way, the metal glows with incandescent heat as lava-like veins lick up the weapon’s length for the next 10 minutes, shedding dim light for 15 feet.
  Bigger Booms. While lit, whenever you hit a target with an attack using this weapon you cause a fiery explosion. Each creature within 5 feet of the target, including yourself, must succeed on a DC 13 Dexterity saving throw taking 1d6 fire damage on a failed save or half as much damage on a success. Flammable objects within this area are set alight if not being worn or carried.
  Rare variant: Increase the DC to 15 and the additional damage to 2d4.
  Very rare variant: Increase the DC to 16 and the additional damage to 2d6.