Fire Sword

The Fire Sword is able to emit and freely manipulate vast amounts of fire, capable of incinerating whatever is in its path. It can be used to send light beams as signals through the green sphere at the end of the blade. It can also be used to summon the Infinite Armour, the Garian Sword, and the Weaknessless Soaring Shortswords.

When Seimei wore the Infinite Armour, he had this sword integrated onto the head of the armour's forehead portion by its hilt.