Zig-Zag Ladder Pattern

[Jeff Pringle]

It looks like an old blade reworked to me, there is a 'modern' feel to the ladder rungs and how they are placed. This would require completely reforging the blade, so unless they started with a heavy blade the finished item would end up noticeably thin or skinny in at least one dimension.
The modern look to the rungs is due to their edges, a little too consistent and different from the ground pattern, combined with the parallel ‘ghost’ lines showing up occasionally, it just screams “angle grinder” to me – compare them to one of Dr. Figiel’s strongly laddered blades, there is a more ‘organic’ feel to the rungs.