Cylferth

Cylferth was an elderly sorcerer and merchant. He sold Dagr and Ebor the Blood Crystals and Stulorne Blades they used to take their revenge on Arthur Pendragon.

Biography
Cylferth sold Dagr and Ebor the Stulorne Blades they used when they attempted to kill Arthur during Camelot's annual Mêlée. Cylferth also enchanted the Blood Crystals they used to enter the tournament in disguise, after which Dagr killed him (Gwaine)

Abilities
Cylferth appeared to be a highly skilled sorcerer, as he used his magic to forge a pair of Stulorne Blades for Dagr and Ebor. He also enchanted two Blood Crystals to allow them to take the form of whoever's blood they touched (Gwaine).

Trivia

 * Cylferth likely lived outside of Camelot, as he openly made and sold magical artifacts (Gwaine).