3 His grated teeth for great disdain, and shook
grated > ground together; hence: clenched disdain > anger, indignation
4 His sandy locks, long hanging down behind, 5 Knotted in blood and dust, for grief of mind 6 That he in odds of arms was conquered; 7 Yet in himself some comfort he did find, 8 That him so noble knight had mastered,