Hi Robert,
very nice catch!

It is a dinahong-palay like you write from Bicol, here a very informative thread:
http://www.vikingsword.com/vb/showth...8&page=1&pp=30
I have a sinampalok, a very similar bolo. I think the varnish on the scabbard is normal, my one has it as well. Age guess would be 1930-1945, WWII area. Barry show his dinahong-palay in this thread, maybe he can confirm the varnished scabbard by his example also.
Great addition to your collection!
Regards,
Detlef