Hi Nathaniel,
While the decorative work does match that ID'd as Kachin in the thread to which you provided a link above, doesn't the blade in your opinion speak to a more likely Karen or Shan origin (as per Ian, Mark and Andrew's article written for the Macao exhibit catalog)? The spine is peaked at the forte, which as per the article is more common to Shan (style) blades. Also, wouldn't it seem odd to present a visiting foreign dignitary with a gift from an area relatively remote from the historical seat of Thai power and influence? Or is there a more prevalent sense of cross-cultural identity that blurs the lines between historically divergent ethnic groups and the stylistic differences as they appear in their respective traditional weaponry?