MT,

I believe your correct about the carbide rusting. I don't know that it would be a problem that would require " nose oil" ;D
Seems you could just blow the excess water off and let dry in sun or wipe dry. I think most ( might be wrong here) fishermen if there filleting regularly like to touch up the edge before each session. I think the don't wash was geared more to using it and storing in a drawer for a length of time before using again.

Kerry,

I'm a big fan of the DMT diamond whetstones. I have the single grit models because when I purchased them, I got a package special.
I have a coarse/medium/extra fine for my kitchen knifes and bought an extra coarse for touching up my camp axe on a trip.
Only drawback for many folks is that you need to know how to hold it and maintain a proper sharpening angle, something the experts even disagree on. I dulled a few before I got the hang of it. Being a fine furniture maker I'm sure you had your moments before you got it down pat ;)

The pocket ones with the pre-set angles are adequate for most people and take the guesswork out of sharpening, if you haven't done it much.
Nothing worse than a dull knife or more dangerous.