Significance of Green Belt :

In lieu of the ring, the lord's wife insists that Gawain accept her green belt as a gift. Gawain refuses until she assures him that it is magic and as long as he wears it he cannot be killed. Gawain takes it, thinking of his meeting with the Green Knight. The belt proves to be Gawain's moral downfall, because he wears the belt out of fear of death. Later, he learns that it has all been a setup by the Green Knight (who is also the lord) and his wife. The belt in not really magic, and when the Green Knight points that out, Gawain is ashamed of himself and returns home dejected at his imperfection. Arthur and the other knights of the round table offer to wear green belts at all times when Gawain tells them his story, as reminders of the possibility of imperfection.