The way in which Sir Gawain demonstrates bravery is when the green knight says to Gawain (pg.81, line-2274) Did I flinch, or flee from you when your blow felled me? (pg.81, lines-2280 & 2281) Gawain replied: Enough! I won't flinch when you hack! This shows bravery, because the second time the green knight swung to chop off his head (another miss) Gawain didn't flinch a bit. Even though Gawain knew he wasn't going to be picking up his head, it still took a lot of bravery to just stand there and remain still while you got this big green knight getting ready to swing at you with a battle ax. The second knightly virtue that Sir Gawain demonstrates in the story "Sir Gawain and the Green Knight" is courage. The way in which Sir Gawain demonstrates courage is when the lord leaves him and is telling Gawain that the knight of the Green Chapel is fierce and deadly, and that he kills every man he meets. He also tells Gawain that he will swear not to say a word about what happened Gawain thanks him and tells him that he must be brave and continue on with his quest. As the lord is leaving Gawain, (pg.71, line- 2156) Gawain says I'll neither groan nor weep. This shows courage in Gawain, because after all of these things that the lord was telling him, he put it all aside and built up the courage to continue on his quest and face the green knight.
The way in which Sir Gawain demonstrates courtesy is after the lady giving Gawain the gift, she starts preying on his desire and knightly obligation to be polite and courteous. (pg.63, line-1771 to 1773) Urgently, spurring him to the brink, and he thinks: 'I must accept her affection, or refuse, and offend her', concerned with courtesy, less he be thought a boor. This shows him having courtesy by him not wanting to stop her in the middle of prey over him.
The first two days he was honest and shared what he got. On the third day while the lord was hunting his wife gives Gawain this magic girdle that she tells him it will save him from the green knight.