I find it much more likely that they would "steel" the blade, over grind it into a rock wall. But a yari maybe..
If you look at the edge of a steel blade under a microscope, no matter how fine a blade it will look like a saw when you get close enough. With a row of teeth that can be bent either direction.
When honing a blade (non nihonto) the final step is/can be, running the blade down a circular piece of steel once on each side of the edge.
This alligns the teeth in a way that leaves the edge more durable to use. I think it probably compresses them so they stay aligned & sharp longer.
I see a very similar parallel between the little knives/tool you find in a saya, and the ones used to steel the blade in other cultures.
If i had to guess i would say that little blade / shiv is not a "camp tool" but possibly for or developed as an impromptu ha repair tool, used like a steel.
Just a guess,
Hank