I just googled cholla, did not know they made handle scales out of cactus. There is some pretty amazing stuff out there.The edge is actually super thin, I don't have a micrometer to measure it, but it got blurry in the picture.
I love this handle material, it's cholla with turquoise
I've never had any luck getting a good choil shot, I think it's near impossible to do it hand held. Like you said, the edge is blurry in the picture so there is no way to tell how thin the knife is. What I was referring to was the second picture, where you can guess how wide the secondary bevel is. I'd say it's around 1mm wide, maybe even a bit over. If you sharpened at 15 degrees per side, the thickness behind the edge would be about 0.5mm/20 thou (2*1mm*sin(15°)). But I'm just guessing from a picture and some assumptions about the sharpening angle, so I might be way off.
You can measure the edge thickness with regular calipers and get a good idea (within a few thou even with the most basic calipers). If you have a set of feeler gauges, you can lock the calipers on a gauge of known thickness and then see if you can insert the blade into the caliper jaws. I like to use locked calipers to see how consistent the edge is based on how far I can insert the blade. It's much quicker than doing multiple measurements with a micrometer.