Flaming sword is a magical large sword. It's essentially the same as the usual long sword, but creates permanent reddish light due to its flames. The flames never disappear, even when the sword is broken.
The flaming sword sometimes burns the victim, causing additional fire damage. Even if the base damage is completely blocked by the monster's armor, resulting in "It is not hurt." message, the flames may still burn the target and even kill it.
The flaming sword can be made of any of the materials a normal long sword can be generated made of.