The most surprising detail here is the number: the cutting edge on this kitchen blade measures about 0.114 mm thick, or roughly 4 to 5 thou, and it bends against a brass roller and comes back straight. That is thinner than anything I would dare to roll in my own shop, and the steel apparently just shrugs it off.
The test itself is dead simple. A short hollow brass cylinder, described by the maker as a piece lying around the garage, sat on a white marble-patterned surface. A thumb pressed the blade face near the edge while the knife slid along the tube from heel toward tip, then the blade was turned around and slid back the other way. The thin cutting bevel deflected slightly under the pressure, showing real edge flex. The blade itself is an unhandled piece with a satin brushed finish and what looks like a clip-point or K-tip profile.
The maker confirmed the movement was genuine flexing, not an optical illusion, and reported that after jamming the blade against the brass tube, careful handling was not needed. In the maker's view, the heat treatment is what gives the blade its strength, and that seems like the right place to credit the result.
Two things remain open. The final edge had not yet been put on, and some hand sanding at the end is still outstanding. Also, the question of whether a flat, hollow or convex grind is what allows this flex went unanswered; only the thickness came back in reply. My own suspicion is that grind geometry matters as much as the 0.114 mm figure, but that is a guess. Either way, seeing steel that thin roll over brass without a set is a sight worth studying.