Final answer:
The Green Knight nicked the neck of Sir Gawain as a test of his honor and courage in the medieval poem 'Sir Gawain and the Green Knight'. The nick on Sir Gawain's neck serves as a reminder to Sir Gawain of his fear and his failure to live up to the chivalric code by withholding the green girdle given to him by the Lady Bertilak, the Green Knight's wife.
Step-by-step explanation:
The Green Knight nicked the neck of Sir Gawain as a test of his honor and courage in the medieval poem 'Sir Gawain and the Green Knight'.
The Green Knight challenged any knight to strike him with his own axe, on the condition that the knight would then receive a return blow in a year and a day. Sir Gawain accepted the challenge, and when he beheaded the Green Knight, the Green Knight merely picked his head up and reminded Gawain of their agreement.
The nick on Sir Gawain's neck serves as a reminder to Sir Gawain of his fear and his failure to live up to the chivalric code by withholding the green girdle given to him by the Lady Bertilak, the Green Knight's wife.