Judging from the display on Thomas Chen's website (
http://thomaschen.freewebspace.com/photo3.html) The Tang dynasty is the place to look.  The angled point with no faceting shown on the Song saber is one I have seen examples of (There is a picture on another page of the same website of what appears to be a Qing copy of Song horse cutting saber with exactly that tip.)  The problem is that I can't tell what the line drawing on Thomas Chen's website is based on.  If it is based on the examples found in Japan we are back where we started.  I found one site (
http://kaladarshan.arts.ohio-state.e...20Buddhism.pdf) that shows a Tang temple, and tantalizingly there is a deity holding a sword, but the tip is not visible... aargh!  If anyone might get to that temple please take a picture.  Another place to go would be the Tang dynasty caves listed here (
http://ignca.nic.in/ks_19020.htm).  I have seen Ming pictures of Tang dynasty personages, but of course the swords they hold are then in the Ming style. In the quick bit of research I have done on this topic I found that the reason Tibetan swords are often cited as being Tang in style is that the Tibetans conquered a large section of China during that time.  So perhaps it is not that Tibetan swords are Tang in style but that Tang swords are Tibetan.  However, Tibetan swords that I have seen do not have a faceted tip or ridgeline, so the focus might have to be non-Tibetan Tang dynasty swords. 
I will continue to look.
Josh