This rare fire-type metal contained a humongous amount of fire-type elemental energy. Its body itself was also incredibly tough. Because it contained fire-type elemental energy, it was resistant to all types of fire—even Ultimate Fire.
This ingredient was often used only for spirit tools which were Class 8 and above because it was particularly hard to shape or carve. Because it was impossible to smelt it, one had to rely on his or her spirit power to force its shape to change. During this process, one had to put up with a fire and poison attack from the Scarlet Devil Essence.
Scarlet Devil Essence was simply too rare and precious.