Gawain answered him never a word but rushed at him, sword drawn, and gave him such a great blow on his helmet
that the strong steel could not keep the sword from going more than a finger deep, and for all Morholt’s strength, he had all he could do to bear the blow. Gawain, who was young and agile, recovered and expected to strike again, but Morholt drew back, and therefore Gawain missed.

Post-Vulgate Merlin