David of Tintagel, Davit
Chrétien lists him among the counts and other vassals whom Arthur summoned to court for the wedding of Erec and Enide. David of Tintagil never suffered sorrow or grief, he had an excellent control over his temper and emotions.
The geography looks wrong for an identification of this David with Saint David.
Sources
Erec | Chrétien de Troyes, late 12th century
Diu Crône | Heinrich von dem Türlin, c. 1230