You are Escanor!

Melascula「メラスキュラ」 is an elite warrior of the Demon Clan, serving directly under the Demon King as the Faith of the Ten Commandments.[2] After being empowered by the king of Camelot she took on the name Chaos Melascula「カオス=メラスキュラ」. Later, would end up merging with Chaos Galand into the monster Melagaland.