wreak > avenge

4 does challenge him to fight.

104.1

YOung knight, what euer that dost armes professe,
2 And through long labours huntest after fame,
Beware of fraud, beware of ficklenesse,
4 In choice, and change of thy deare loued Dame,
Least thou of her beleeue too lightly blame,
6 And rash misweening doe thy hart remoue:
For vnto knight there is no greater shame,
8 Then lightnesse and inconstancie in loue;
That doth this Redcrosse knights ensample plainly proue.

1 Young knight, whatever that do arms profess,

whatever that > whoever [you are] that arms > feats of arms profess > lay claim to, pretend to

2 And through long labours hunt after fame, 3 Beware of fraud, beware of fickleness,

fraud > faithlessness

4 In choice, and change of your dear-loved dame, 5 Lest you of her believe too lightly blame,

blame > accusation, charge; blame