many characters and events associated with him, indicating a once well known story now lost.

He is the owner of one of the Thirteen Treasures of the Island of Britain: a magical sword called Dyrnwyn (white-hilt). The list also attempts to justify Rhydderch's epithet 'Hael' in describing the sword: "if a well-born man drew it himself, it burst into flame from its hilt to its tip. And everyone who used to ask for it would receive; but because of this peculiarity everyone