sire > elderly man trace > walk, proceed (with added connotation of tracking or pursuing)

4 And far before a lightfoot page did fly,

before > in front lightfoot > light-footed

5 That breathed strife and troublous enmity; 6 Those were the two sons of Acrates old, 7 Who, meeting erst with Archimago sly,

erst > recently (see 206.47)

8 Forby that Idle strand, of him were told

Forby > hard by, near strand > shore of > by

9 That he, who erst them combatted, was Guyon bold.

208.11

Which to auenge on him they dearely vowd,
2 Where euer that on ground they mote him fynd;
False Archimage prouokt their courage prowd,
4 And +stryfull+ Atin in their stubborne mynd
Coles of contention and whot vengeance tynd.
6 Now bene they come, whereas the Palmer sate,
Keeping that slombred corse to him assynd;
8 Well knew they both his person, sith of late
With him in bloudie armes they rashly did debate.