arms > armour (see I:171-3)
3 Wherein old dints of deep wounds did remain,
dints > dents, indentations
4 The cruel marks of many a bloody field;
field > field of battle, battle
5 Yet arms till that time did he never wield.
never wield > (See I:152 ff.: "In the beginning of the feast …")
6 His angry steed did chide his foaming bit, 7 As much disdaining to the curb to yield: 8 Full jolly knight he seemed, and fair did sit,
Full > [A] very jolly > gallant; handsome; fine; also, apparent only on a second reading of Book I, in the rarer pejorative senses: self- confident, arrogant, lustful fair > expertly sit > sit in the saddle; ride
9 As one for knightly jousts and fierce encounters fit.