"it is strange that none of the sisters recognise him, or that he doesn't recognise them"
Fairly common motif in traditional songs and stories and has been for a long time - I think Odysseus had the same thing happen to him (though he did make an effort not to be recognised).
An interesting parallel between the broken-token songs and Mrs Gaskell's 19th century 'Sylvia's Lovers' where the sailor returning from the war is not recognised by his sweetheart because he had been burned by the backfire of a cannon (if memory serves me right).
Jim Carroll