There are a lot of specialized sharpening devices out there. everything from that big glorified rat tail file you see cooks often using as a knife sharpener, to flat stones, to contraptions with guides and ceramic wheels. I was recently given a Speedy Sharp tool sharpener, by the best landscape designer I know, and I think it is enough of an improvement over the others in a general purpose sense to have achieved design perfection.
The Speedy Sharp isn’t much more complicated than it looks, just a well shaped chunk of carbide with a rubberized grip, but it works better than you would imagine. I don’t think I’ve ever needed more than a few swipes to sharpen anything and it doesn’t chatter or leave rough spots, and it is small enough to not take up a noticeable amount of room wherever you may keep or carry it. It is great for tools or sharpening knives.
I’ve been using my Speedy sharp for six years now and it looks like it did the day I got it.