They're really not. All you need is an angle guide you stick to the knife. Something like https://setamono.co.za/products/knife-sharpening-angle-retai...

With that all you need to do is pretty much go back and forth. Note that the whetstone eventually wears them out too.

Something to grab while you're at it, is a truing stone to take care of the whetstone as it _will_ wear out unevenly making the sharpening a pain.

Thats 2-3 extras over rolling sharpeners