Clarysyn
In the Alliterative Morte Arthure, a city in Lorraine, captured by Arthur during the Roman War.
After defeating the Duke of Lorraine in combat, Arthur prepared to conquer the city by assault, but the Countess of Crasine convinced him to take it peacefully.
Malory gives the name to the countess herself.
Sources
Alliterative Morte Arthure | c. 1400
Le Morte Darthur | Sir Thomas Malory, 1469-1470