Weapon, Rare (requires attunement; cost 5000 gp)
A written contract with a devil or other extraplanar and fiery entity
While you are attuned to this magic sword, you can use a bonus action and speak its command word to make flames erupt from the blade, shedding bright light in a 40-foot radius and dim light for an additional 40 feet. While lit, attacks using the sword deal an extra 2d6 fire damage. The flames last until you use a bonus action to put them out or until you drop or sheathe the sword.