Possible Clues:

• Legendary knight's weapon, auction item
• Arthurian knight taking his weapon back to lake
• Arthurian knight takes his weapon back to lake
• Knight who stormed Swamp Castle in 'Monty Python and the Holy Grail'
• In Arthurian legend, the father of Galahad
• One knight of the Round Table
• Knight provides weapon to many
• Look through window to see legendary adulterer
• Percival wants something to knock down Round Table colleague
• Knight of the Round Table and close friend of King Arthur's wife, Guinevere