The name was gained when the Duke rode in a charge that was all but doomed most likely a few riders being lead against a larger force. The individual acts as a beacon of hope for soldiers acting as vanguard.
The knight has a spear that has been augmented the name also wreath both the rider and the mount with light protecting them as well as increasing offensive power.
The Name is especially powerful when leading a vanguard of soldiers in a charge, effectively changing the tide of a battle by massing into a spear of death shredding enemies wherever they go. This makes the weakness of this name apparent, without weapon or a horse the name is crippled.
Felix Caen: The, Duke of Liesse, Felix had been the glory of Callow’s knighthood long before he led the doomed charge in the East that earned him his Name.