The Horns of Valmar are a piece of the dark god sealed away after The Battle of Good and Evil to await a human host. The horns were sealed away on the Island of Garlan within Grail Mountain. Whether part of the sealing process or placed there afterwards, this site became home to a powerful sword, known to the locals as the Idol. Only the greatest swordsman in the world could wield the sword.
When the seal becomes active, the Village Chief's daughter is the first person to come into contact with the site and becomes possessed by the Horns of Valmar. When Melfice is sent to rescue Reena with several other villagers, he eventually ends up killing them all and stabbing Reena through the chest with the Idol sword. In doing so, Melfice absorbs the power of the horns for himself.
The Horns within MelficeEdit
Unlike most of the other parts of Valmar, the horns do not bring about a large physical transformation in Melfice. He is seen with a large horn upon his forehead but physically appears human otherwise. With the power of the horns, Melfice sets about to do Valmar's will by destroying those who pose a threat to his power. Like others possessed by Valmar, he also intended to find the other pieces of the dark god. However, while Melifice succeeded in finding the Claws of Valmar, he did not absorb them himself but left them within an automata under his control.
The Horns within RyudoEdit
When Melfice is killed in battle by Ryudo, the horns jump to the closest powerful host. Ryudo absorbs the horns but attempts to resist the power. Ryudo falls unconscious and must fight the darker urges within himself in order to keep the horns at bay. He succeeds in hiding the power in himself but does not truly confront the problem until he reached the Birthplace of the Gods where Elmo uses the laboratory to unlock the power of the horns within Ryudo. He tells Ryudo that he must be entirely pure of heart in order to prevent Valmar twisting him into his servant.
Ryudo initially fails and becomes a vile monster of Valmar. However, he continues to fight and eventually returns himself to his true form, granting him the power of the Granasaber in order to thwart the resurrected Valmar.