Cerceus

Cerceus is the sword god who trains Seiya after he defeats one of the Four Heavenly Kings. He was formally a human warrior, but was reincarnated as a god after his passing. He retains almost no memories of his time as a mortal.

Personality
Cerceus is a god confident in his sword skills. He does however, have a weak side that comes from when he was a human. This side peeked out while he trained Seiya and caused him to completely lose confidence in his abilities to the point where he never wanted to see a sword again and took up the more passive pastime of cooking. Cerceus comes back to his old self however after training Mash, realizing that he was still a strong fighter and that Seiya was just an extraordinary outlier.