There may be more than one in any sharpening job but what bit would you use to sharpen knives?

 

Unless the knife has some horrible nicks I wouldn't use any power device on it. Most knives can be sharpened with just a whetstone and a little elbow grease. Sometimes the butcher shop in your local supermarket will offer knife sharpening for a small fee.

 

Agree with Furd, I would never use a power tool, let alone a Dremel, to sharpen a knife.

This is what I use: https://www.spyderco.com/catalog/details/204MF/77
FWIW, I don't recall paying anything near three figures for it but I have had it maybe a couple decades now.

 

For a real dinged up or chipped blade, it may indeed need to be reshaped and a new edge put on. It's a job for a specialist with specialized equipment. Unless you want to invest a $1000 or so in a sander/ grinder and buffer. Small nicks can often be taken out with a carbide pull across type sharpener like those from Lansky and others. It will put a coarse edge on which can be refined with stones and hones. A Dremel isn't the tool for this job.

 

Learning to sharpen a knife by hand with a whetstone is an art every man should learn. And then teach to his sons. That's what I still do with "lesser" and utility blades, but for expensive knives and the ones I'm sentimentally attached to, I use a 5-stone Lansky knife sharpener. The Lansky basically is a jig that maintains the knife blade and the whetstone at a consistent angle during the sharpening process.



The advantage of devices like the Lansky (and there are others) is that they maintain a consistent angle between the blade and the stone, which makes it possible for even a novice to keep a razor's edge on any blade, and they largely prevent marring of the blade where you aren't sharpening (which is near unavoidable with "hand sharpening"). Which is purely a cosmetic consideration but I have knives I'm attached to and like keeping them as unblemished as possible.

A crock stick like stickshift recommended can work well for touch-up jobs, but if you need to cut a new bevel angle or if the edge is damaged, you'll need a coarse whetstone. That's why the Lansky kit has five stones, ranging from coarse (which I very rarely use) down to a very fine "soapstone" for the final polish. Which isn't really the "final" polish, because the razor strop comes after.

I might use a powered sharpener on something like a machete or an axe but I'd sooner use a dremel tool on my teeth than a knife I care anything about.

Dead blunt to razor sharp with a Lansky (video)