appeached > shamed, dishonoured

3 And inward grief, he fiercely gan approach,

gan > did

4 Resolved to put away that loathly blame,

put away > dispel, put an end to loathly > loathsome, hateful

5 Or die with honour and desert of fame;

desert > merit, reward

6 And on the hauberk struck the prince so sore

hauberk > {Chain-mail tunic; chain-mail covering for neck and shoulders} sore > grievously

7 That quite disparted all the linked frame,