3 For well he weened that so glorious bait
weened > supposed so > such [a]
4 Would tempt his guest, to take thereof assay:
assay > test, trial; hence: a sample
5 Had he so done, he had him snatched away,
he had him snatched > [the fiend would have snatched him]
6 More light than culver in the falcon's fist.
light > quickly; easily culver > dove; wood-pigeon fist > clutch, clutches
7 (Eternal God you save from such decay!)
decay > [a] downfall