Philippine monosteel Blades. Preserving and restoring

[oldschldude]

Hello.
I'm back with pics. Finally figured out how to compress photos using MS Paint.

Most info that I read about rust removal or blade restoration was on laminated Philippine blades. Didn't know if etching also applies to mono steal.
I'm attaching my barong pics that I would like to clean the blade. It started to get dark spots and small pits. I would hate to ruin it by improperly cleaning the blade. I would like to get rid of the dark spots and don't know if etching it would ruin the blade or change to different color. I will use warm vinegar if I will etch it.
I never etched a blade before, I only apply oil to preserve it. Most of my info in blade restoration I got here and I think this barong is mono steel. One question is, When did the filipinos start using leafsprings? WW2 era or before that like in Span-Am War. Thanks again everyone. Oldschldude