Two entries with the name Guinebal.
Guinebal
Guinbat, Guinbating
A Saxon warrior slain by Agravain at the battle of Logres.
Sources
Vulgate Merlin | 1220-1235
Arthour and Merlin | Late 13th century
Guinebal
Guimbaut, Guinebaut, Gwenbaus
The older brother of Kings Ban and Bors and the uncle of Lancelot.
He was a wise cleric, a skilled fighter, an amateur magician, and a tutor for his brothers as youths. Bors gave him the castle of Charroie.
Guinebal became fast friends with Merlin when his brothers joined Arthur’s wars against the Saxons and the rebellious kings. Merlin was impressed with Guinebal’s knowledge, and added to his repertoire of magic.
Guinebal fell in love with the Lady of the Inhospitable Land Upheld when he met her in the Perilous Forest. For her love, he created a number of marvels, including the Magic Dance, which ensnared any passers-by, and a magic chessboard which moved its own pieces against any willing player, and invariably defeated him. Because of his enchantments, the forest was re-named the Forest of No Return. Guinebal died after teaching the lady some magic.
Sources
Vulgate Merlin | 1220-1235
Arthour and Merlin | Late 13th century
Le Morte Darthur | Sir Thomas Malory, 1469-1470