King Arthur of Camelot wields his magic sword Excalibur as protection against his enemies. This may include Black Knights and any Frenchmen who dare taunt him a second time.
Given the Celtic roots of Arthurian legend, I always preferred to imagine Arthur as a Celtic tribal chieftain instead of the traditional medieval king in a castle. He looks more interesting that way since we don’t hear about Celtic tribespeople as often as we do medieval and Greco-Roman history.
The horned helmet is artistic license on my part, but horned helmets actually have been recovered from European archaeological sites (though ironically none of them date to the Viking period in Scandinavia).