Joyeuse: (聖剣ジュワユーズ, Seiken Juwayūzu?) is a Noble Phantasm of Karl der Große and Charlemagne. It doesn't appear in history books or chronicles, a famed sword mentioned in various chanson de geste. It appears in the "Song of Roland" where it is a peerless sword. Its colors changes 30 times a day. In addition, it is said that the head of the holy lance Longinus is stored inside its pommel as an artifact. The name means "merry" or "joy" in French.
Though both Charlemagne and Karl der Große both possess this Noble Phantasm, Karl, having lived and being rooted in history rather than legend, is unable to use it to its full potential. They both differ slightly, Charlemagne's version being a blue and silver longsword sheathed at his waist, while Karl's is a gold and black greatsword as long as he is tall.