The achang dha

[JBG163]

Dear all,
I just acquired an achang dha (can't post pictures for now on as i didn't received it) and i would like to get more information concerning them.
I dug every threads about them in the forum but i would like to ask if someone have references concerning those swords.
Ian looks to be the most knowledgeable forumnite on the subject, and, honestly, i would be really happy if you could help me !
The handle is classic burmese silver, no guard, scabbard is open faced and there is a carved pannel. Blade is probably hairpin patterned and quench is quite visible

My precise questions are :
"What does discriminate that sword as an Achang dha ? Is it the pannel or the open faced scabbard ?"
"Does it exist exemple in museum collection that you all are aware off ?"
"Does it exist any books, catalogue or any references talking about them and pinpointing the tribe?"

Thanks all in advance !
I look forward to read you
Best,
Julien