A knight who, with his brother Sir Hugh (Hue), stole lands from the Lady of the Rock. Yvain championing the lady, called for a duel against one of the brothers, but the brothers insisted that Yvain fight them both at the same time. Yvain won the battle, killing Edward and wounding Hugh.
I have found a post-it note that Sir Marhaus fought and won the lands back. I will see if I can find the source.
Source
Le Morte Darthur | Sir Thomas Malory, 1469-1470