Thanks for the nice comments Everyone.
I used to make quite a few hunting knives that had a similar handle shape, but with a flat back/no thumb ramp. The cross section was about the same, but the handle was much longer.
Then I made myself a little belt knife for EDC, and while I liked the concept, I wanted a little thinner point, and I found the grip wasn't quite right. It needed something to make up for being shortened. I used that knife for over a year and it was great for most things, but if you needed to cut something hard like shaving the end down on a pitchfork handle to fit in the socket, it was hard to get much purchase. When you can't grip the heel with your pinky, your thumb has to do more work.
I remembered a couple somewhat "fighter" style knives I made a long time ago that had a thumb ramp and thought the idea might help make up for the short grip, so I kind of adapted the 2 ideas together.