4 Deep indignation and compassion frail
frail > tender (SUS)
5 Into his heart at once: straight did he hale
at once > simultaneously; at once straight > straightway, unreservedly; strait: strictly hale > drag
6 The greedy villein from his hoped prey,
villein > villain; serf hoped > [hoped-for]
7 Of which he now did very little fail,
fail > lack (fail of = miss)
8 And with his staff, that drives his herd astray,
astray > [when they are astray; hence: when they stray from their proper course]