2 Her single person to their barbarous truth,
single > solitary truth > {Allegiance; conduct in accordance with the divine standard; also: a variant spelling of "troth", good faith}
3 But still 'twixt fear and hope amazed does sit,
amazed > astounded
4 Late learned what harm to hasty trust ensues;
Late > Recently learned > taught; having learned
5 They, in compassion of her tender youth, 6 And wonder of her beauty sovereign,
of > at
7 Are won with pity and unwonted ruth,
won > overcome unwonted ruth > unaccustomed pity