It was a pretty awful ending for what it was, but it was a pretty damn awesome ending for what it meant, and that feeling of exhilaration and "OH SHIT, SON!" every time the giant mirrors are revealed and Shenhua starts reciting the poem. C'mon, who doesn't get that amazing feeling each and every time?
As for the floating sword? Symbolism, a sign-posting that magic would be entering the Shenmue universe, or maybe even just for the purpose of getting a pretty screenshot to end the game with? Hmm...
xx