It would not be the first time that I am "chalk full of blueberry muffins..."
and I agree that Museums can make mistakes. I also think that since the Spanish has about 400 years to learn about P.I. swords, there maybe something to learn from their experience... especially when verified with other examples.
Check the below link on Parang Naburs and compare the blade profiles below.
http://www.vikingsword.com/vb/showth...y+parang+nabur
It seems to me that this profile is unique in the Philippines. If it is not a Parang Nabur (and can we prove that it is not related), then... what is it? The Spanish may have got this right, that it is a Philippine version of the Parang Nabur. All of the key ingredients are present (except for the peen).