Why did excalibur break when arthur used it in his fight with lancelot?

Excalibur broke during Arthur's fight with Lancelot due to the intense emotional and physical turmoil of their battle, which symbolized the fracture in Arthur's ideals of chivalry and loyalty. The sWord, often seen as a symbol of divine right and unity, shattered as a reflection of Arthur's internal conflict and the disintegration of his kingdom. This moment highlights the tragic consequences of betrayal and the inevitable decline of Arthur's rule.