If you are in freshwater almost anything will work. In saltwater, steel rusts unless you rinse and dry it after every use.

I use one I made. A balisong made of talonite (cobolt 6BH) The talonite will not rust. I have some talonite on my work bench marked for a fixed blade rescue knife, I just have not had time to finish it.

David Boye makes a cast cobolt folding knife, that is very good. In the past he has made fixed blade cobolt knives that can be finished as a kit. I do not know of a current source for those.

The pointed Gerber river knife is my favoite style. It works well if you keep it clean. I am not a fan of the blount points or hooks because the point is a valuable cutting surface. It's the fastest way to open a hole in something covering you. For example, a tramp you are trapped under it.

The best sheath I have seen is a plastic quick release with a nylon and velcro cover over it. It's like an open sided pouch over a sheath. It is unusual for these sheaths to release by accident. You can make your own by adding a cover or a wide strap to a conventional sheath.

Carl