When I was a kid my Dad had one of these Lansky knife sharpening kits. It came with a bike grip style handle that the clamping bracket slotted into. They don't seem to sell that accessory anymore. I can't even find a picture of it online. I've recreated it here. I feel like this is little more ergonomic than the pillar type holder.

The clamp from the Lansky kit slots into the top of the handle and you hold the base with one hand while holding the sharpening stone with the other. It's ambidextrous so no need to mirror it. There are screw holds on the base if you want to lock the handle down to a workbench or something.

I've designed this for the handle to fit my hand, and the for the clamp from my kit (circa 2016) to fit into it very snugly based on the tolerances of my printer. I've included the STEP file if you need to resize anywhere.

I printed the one in the picture at 0.24mm layer height in Overture brand black PETG. You can see in the photos I'm still working on my PETG settings, there is pitting in the top surface of that print, but it does work functionally.