Suddenly so formal! I mean, they’ve already been you-ing it, up with the formal You instead of thee and thou but this farewell (where are we in the count?) has a YOU in the middle! This would seem to make a farewell more specific and perhaps also more personal. I could say Farewell to the crowd and the people in it when I say Farewell but a Fare You Well would suggest only you that I’m saying goodbye to.