Hello Ian,
thank you very much for your well researched respond!
And I agree with you in all points.
I think it's not only the problem by the "minasbad" but also by nearly all ethnograhic weapons to find a "solid basis" for a name for it. I only want to remember the term from Alan: "name game" which I like very much, collectors like to give their toys a name. We need to recognize that the same weapon can have different names in different regional parts of an island.
But I think we have a good quintessence already with this sentence from you:
What we might reasonably conclude, IMO, is that the sword is likely found in Camarines sur, a part of the Bicol region, and there it may be called a minasbad. This does not exclude the sword being found more widely in the Bicol Region or elsewhere, nor does it exclude the sword being called something else in Camarines sur or elsewhere.
Everybody who is interested in swords from Luzon will know which sort of sword is meant when we call it "minasbad".
Best regards,
Detlef