It's a fairly rare, rather obscure and somewhat archaic (although still in use) form, where the verb return combines the action (of returning) and features of the word become.
It's rarely used in other contexts.
he returned a hero,
he returned a coward,
he returned a disgrace to his nation
These should be understood as he became [something], as he returned.
There is nothing missing, it's just a rare way of phrasing this kind of sentence, where the word "return" obtains an extra grammatical property of acting like "become".
There are some more words that can obtain this property; combining motion and "morphing" - but you'll see them even more rarely in this form: "appear", "arise", "emerge", "depart".
he departed a boy, and returned a man.
