Certes > Assuredly shame > feel shame, feel ashamed

2 The fond encheason that me hither led.

fond > foolish encheason > cause, reason

3 A false infamous faitour late befell

faitour > impostor, cheat late > recently

4 Me to meet, that seemed ill-bested,

ill-bested > hard-pressed, threatened, in trouble (bested = placed)

5 And plained of grievous outrage, which he read

plained > complained read > [had] observed; declared, made known

6 A knight had wrought against a lady gent;