I sometimes get the opportunity to use other makers' knives:

Fillet knife video

(Keep in mind this was made for my friends and customers who may or may not be familiar with the B'dub.)

That's a beauty. Is there a difference to sharpening filet knives vs. a standard blade? How would YOU keep this blade sharp?

that's an excellent question. We have a saying in the knife industry that a knife should only be sharpened one time - when the maker makes it.
After that it's the responsibility of the user to KEEP it sharp.
It should always be sharp.
Just strop it a little after each use on whatever is at hand.
I carry a small diamond-plated "thing" with me when I know I'll be using my knives.
If you have an interest in really nice and simple tooling to keep your knives sharp at home rather than become an expert at stone sharpening, check out "Wicked Edge" I saw these guys demoing in Atlanta last month and I was VERY impressed.
I have all sorts of mechanized instruments here in my shop, but I still think I'll get the bottom of the line model:
Wicked Edge "GO"

First in a series:

Demo

Thanks Karl!