I use a handmade damascus steel knife for saltwater because that is what I have and I wanted to test it. At the end of a days fishing, being used multiple times to cut bait, it would have some surface rust on it. I would take it home, wash it in the sink, then put a light coat of oil on it. That is all it took to clean it up and have it ready for next time. SO.... if you find a knife that you like that isn't a "salt water" knife, you can still make it work, just a little extra cleanup, that only takes a minute or two.
I left it one time in the sheath for a few days without washing it after fishing, and it just took a little buffing with steel wool to clean it up like new again.