Sword blinds people

Thereupon they heard a call made for Kadwr, Earl of Cornwall, and behold
he arose with the sword of Arthur in his hand.  And the similitude of two
serpents was upon the sword in gold.  And when the sword was drawn from
its scabbard, it seemed as if two flames of fire burst forth from the
jaws of the serpents, and then, so wonderful was the sword, that it was
hard for any one to look upon it.  And the host became still, and the
tumult ceased, and the Earl returned to the tent.