Darkblade was a swordsman who lived in medieval Paris, the ruler of Paris for a period of time, and the ancestor of Armand D'Argencourt.
During the medieval times, Darkblade took over Paris, ruling over it with an iron fist. However, later, a wealthy Frenchman won Paris' citizens over with underhanded means, overthrowing Darkblade and ending his reign.
Darkblade was a highly skilled swordsman. Due to his skill with the blade, he invented his own special technique, which involves pretending to be open for attack, just to suddenly fight back and knock his opponent's weapon away. As seen in Armand's explanation of him, Darkblade was also capable of using a lance and riding a horse.