This was easier to do than it is to describe but let’s see how it goes.
The first step was to make a component of your knife geometry. Then I made a copy of the component and scaled the copy up by a factor of 1000. This will help to prevent possible issues with short edges and holes.
I drew the curve profile for the hollow grind at the tip and at the shank end. They’re shown highlighted above. I use Bezier curve drawn with Fredo’s BZ-Spline extension. I also erased the top face and the unneeded edges.
The curve along the knife edge and the one at the top of the bevel got weld with TIG-Weld from Sketchucation. Then the four curves were selected and I started Fredo’s Curviloft.
You’ll have to play with the settings to see what works best for you. The resulting surface will be a group. Explode it.
I pushed the bottom face of the knife up to make it half the thickness of the original blank. In the next steps the remaining geometry will get copied, flipped along the blue direction and joined to the original.
After the two halves are moved together, the large copy of the component is closed. (Exit edit mode) Then the large copy can be deleted and Zoom Extents will return you to the original.
