5 On equal plain, and there so hard beset;

equal > level (physically); equitable, impartial

6 Even the famous Britomart it was, 7 Whom strange adventure did from Britain fetch,

adventure > fortune, occurrence

8 To seek her lover (love far sought, alas), 9 Whose image she had seen in Venus' looking-glass.

Venus' looking-glass > (The magic globe described at 302.18-21)

301.9

Full of disdainefull wrath, he fierce vprose,
2 For to reuenge that foule reprochfull shame,
And snatching his bright sword began to close
4 With her on foot, and stoutly forward came;
Die rather would he, then endure that same.
6 Which when his Palmer saw, he gan to feare
His toward perill and vntoward blame,
8 Which by that new rencounter he should reare:
For death sate on the point of that enchaunted speare.

1 Full of disdainful wrath, he fierce uprose

disdainful > angry, indignant