Here's what rhymes with unassail.
fail sale sail avail veil hail shale vale assail hale faille male scale mail pale tail tale jail nail rail frail gale whale bail stale wail bale dale pail snail flail kale unveil wale trail email travail curtail inhale quail quale braille mainsail grail wassail hightail lugsail carrell detail prevail entail exhale bewail derail gunwale topsail countervail foresail impale monorail taffrail hangnail fingernail pigtail ponytail bobtail nonpareil pellmell martingale swallowtail tattletale