Flaming Weapon Fusion
(from Starfinder Core Rulebook)
The flaming fusion imbues a weapon with the fiery power of a star. Half the weapon’s damage type is replaced with fire damage. You can activate or deactivate the flaming fusion as a swift action. If the weapon already deals two types of damage, replace one of them with fire (you decide which damage type to replace each time you activate the flaming fusion). You can add this fusion only to a weapon that does not already deal fire damage. This fusion never causes a weapon that normally targets KAC to target EAC.