Hi Tim,
I think "Temple Dha" is one of those imprecise self-perpetuating terms that has fallen into common use in the west. It's easier to say that than "a decorative Burmese sword with repouse'd white metal fittings and a poorly made blade with silver and/or copper wire koftgari typically depicting figures and text in Burmese".
When someone says "temple dha", I immediately know what they are referring to.
Not all swords of this design are cheap tourist or decorative weapons, but I suspect most examples now on the market are newly made for sale to tourists or for decoration. It does sound like you have one of the nice examples.
Puff has my expanded my understanding of Thai ceremonial sword use (thanks, Puff!). I also understand that some ethnic groups in the region (e.g. Mien and Kachin) do use dha in various ceremonies and blessings, and dha with blessings inscribed on the blade are known.
Unfortunately, I fear that until we can develop better contacts in Myanmar, definitive answers about Burmese "temple" swords will elude us.
Best,
Andrew