Carlos, My congratulations for your acquiring this VERY interesting piece for your collection.!!! If I had more money to spend you would not have gotten off so cheap.
Just kidding, I am very happy for you on being able to obtain this unique item. Myself I do not think the hilt was from another weapon but was purposely made for this knife.
Rick, It is hard to say which way this went. As Dimasalang has suggested the insignia could have been captured from the Spanish and then used as a personnel "anting anting" or the other way around with the knife being captured by the Spanish and then personalized by who ever was in possession of it at that point in time. As for the lug at the end of the pommel that is a common trait for knives from Luzon and I do believe that this sheath is original to the knife.
Dimasalang, Thank you so much for identifying this insignia (it was driving me nutz) as being Spanish in origin. The closest I could find was the button that I posted above but not the badge itself.
Robert