Tanks a blow to the face and kills Emperor

And either smote other fiercely, and at last Lucius smote Arthur thwart the visage, and gave him a large wound. And when King Arthur felt himself hurt, anon he smote him again with Excalibur that it cleft his head, from the summit of his head, and stinted not till it came to his breast. And then the emperor fell down dead and there ended his life.

Le Mort D'Arthur