Mindanao Spear turned into dagger

[Pinoy Blade Hunter]

I recently got this from an antiques store. A spear head mounted on a hilt.

Some say this might be Maranao, or a lumad spear mounted by a Maranao craftsman. soaked the blade in vinegar overnight, but the rust pits are too deep. i need to sand a bit more to even it out and expose the laminated edge better.

how common are these "transformed" spears?

does it have a new name if the spearhead becomes a dagger?