I almost bid on that piece.
This is unusual since most of the northern pieces with wavy blades are Illocos Norte in origin. I have only seen these from Illocanos. Thus I question the Negras origin.
On the Katipunan question, the sun with a face is a definite Katipunan emblem and was in fact incorporated later into the Malolos flag when the government as set up around latge 1899. It is a form of Malay sun and the rays in this case represent the 8 original provinces that revolted this last time against the Spanish. Later some of the Visayas revolted, like Bohol island, Negros, etc.
The star in the middle of the hilt in this case -
Bill - yours is the best example I have ever seen (grumble,grumble,envy,envy

). I would add that it may have belonged to a general.
Oh yes, here is that post:
http://www.vikingsword.com/ubb/Forum1/HTML/002102.html