Final answer:
Men fear death or grave injury if the Green Knight strikes a blow with his axe, reflecting the dangerous reality of medieval warfare and the formidable nature of the Green Knight.
Step-by-step explanation:
The question is about the fears men might have regarding the Green Knight striking a blow with his axe. From the context provided, it seems this scenario is part of a literary work where knights and warfare play a significant role. Men likely fear that if the Green Knight delivers a blow with his axe, it could result in death or grave injury to those on the receiving end. This fear is consistent with the themes of chivalry, the often-overwhelming nature of medieval combat, and the power wielded by such a formidable opponent. The imagery of knights at Camelot crossing themselves in fear and the technological shift rendering individual heroism obsolete suggests the formidable and frightening presence of the Green Knight, possibly linked to the consequences of battle.