1 "To which when she your courage has inclined

courage > spirit, heart; sexual desire

2 Through foolish pity, then her guileful bait

bait > temptation

3 She will embosom deeper in your mind,

embosom > enclose; implant

4 And for your ruin at the last await."

await > {Watch for a chance of contriving}

5 The knight was ruled, and the boatman strait

strait > strictly (if referring to the action); strict (if referring to the boatman)