When I use my awesome cleaver for a long time, my index finger suffers. It's particularly bad when my hands are wet & I'm cutting hard vegetables.
It's the spine of the knife. It has hard right angles that dig into the base of my index finger as I apply pressure. Maybe I'm the only one who has this problem, but if you have it too, here's an easy solution.
You can soften the corners just a little with your knife sharpening kit. I have an Edge Pro Apex 3, but any whetstone will do.
Start with a medium (220) or fine (400) stone and wet it as normal. Gently take a little material off of the corners of the spine where it meets the base of your index finger.
Next, use a very fine (600) stone to smooth out any scratch marks. You could go all the way to 1000 grit to restore the shine if you like.
It works like a charm. Do yourself a favor and make your tool more comfortable. Mrs. Mojo liked it enough that she asked me to do her knife too.