The demon empowers the knight from within the safety of his armor. Undeterred by his body having been mostly consumed by the demon, the knight gallops into battle. For battle is all he knows and his sole justification for existing.
A knight is a person granted an honorary title of knighthood by a monarch or other political leader for service to the Monarch or country, especially in a military capacity. Historically, in Europe, knighthood has been conferred upon mounted warriors. During the High Middle Ages, knighthood was considered a class of lower nobility. By the Late Middle Ages, the rank had become associated with the ideals of chivalry, a code of conduct for the perfect courtly Christian warrior. Often, a knight was a vassal who served as a fighter for a lord, with payment in the form of land holdings. The lords trusted the knights, who were skilled in battle on horseback. Since the early modern period, the title of knight is purely honorific, usually bestowed by a monarch, as in the British honours system, often for non-military service to the country.
See Defiled Ebony Knight.