Proctologically Violated©® writes:

But in looking at some chinese tooling, it sort of looks like
brass/bronze brazing rod was used. Mebbe even the fluxless stuff that
the hvac peeple use??

I don't know that the color appearance is much help identifying an alloy.
The pricey 45 percent silver stuff still has a gold or brass color.

I forget where I researched this, but the cadmium and high silver alloy is
said to be critical to getting a shock-resistant braze on carbide. The
more common HVAC rods I presume would be more prone to snap off.

I have used the silver/cadmium rods, with the Allstate S-200 flux, on a
number of hand and power tools, and it has always wetted easily, filled and
filleted nicely, and held up superbly, with nothing more than Turbotorch
propane/air flame.