The Ars moriendi is a custom made Prototype Knightmare Frame of the soon to be developed Vincent.This Knightmare is the personal frame belonging to Arthur Ni Britannia, the 5th prince of Britannia. The Knightmare is a prototype, but operates just as well as the Lancelot. it incorporates technology from the Gawain, a Knightmare Frame stolen by the Black Knights.
This Knightmare bears a striking resemblance to The Vincent Commander type, yet the color scheme was changed to black and crimson in the favor of Arthur himself.
The Ars Moriendi was developed durig the first stages of the Black Rebellion. It was developed by Arthur and Lucas' Knightmare Development corp., Zeon. It was then given special changes, including the movement of the Factspheres to the eyes, and replacing the usual area with a hadron cannon. The knightmare was given two Maser Vibration Swords, a Druid system, a Geass conductor, and slash harkens coming from the shoulders.
It was first piloted by Arthur in a single-unit assault on the rebels in Area 6. The rebels planned to destroy the entire Rio De Janeiro settlement, yet Arthur single-handedly faced 300 Glasgow units, and defeated all, leaving no survivors. After the massacre, as surprise attack was launched by the leader, Raul Vasquez, and a squad of smuggled Gloucesters, yet all were defeated with ease.
At least a month afterward, during the Assault on Tokyo, Arthur was challenged to a duel by Kyoshiro Todoh, and was defeated, leaving the Ars moriendi heavily damaged. Fortunately, Arthur survived, as well as 40% of his knightmare.