Material Analysis: Matched Pair of Antique Philippine Blades with Crystalline Matrix

[Oiluj13]

Hello everyone,
This is my first post on the forum—thanks for adding me! I am seeking your collective expertise to help identify a highly unique group of antique Philippine blades
My primary goal is to bring the unique composition and internal metal matrix of the matching twin pair into focus for the group.
Unlike standard acid etching or rust pitting, the steel on these two companion blades displays a dense, smooth, high-contrast micro-crystalline structure that is entirely flush with the surface plane. The pattern becomes intensely reactive and shows distinct optical chatoyancy under glancing, sideways light.
To help with the analysis, I have included a close-up image contrasting all three types of steel in my collection side-by-side: the granular crystalline matrix of the twin set, a heavily layered pattern-welded blade, and a standard carbon steel edge. I would deeply appreciate your insights on:
The Steel Matrix: What specific type of crucible or specialized lamination method is responsible for this smooth, granular, micro-carbide crystal segregation?

Thank you very much for your time, analysis, and guidance!

[Lee]

The 'patina' and rough finish could be obscuring something, but these appear to be tool grade and made with a 'modern' steel. I have a few Philippine pieces from the 1980s that they remind me of. Serviceable and fit for their intended function.