...As for rust well, for field knives let them darken naturally or cut acidic fruits to speed up the process. The oxidation layer will protect the blade well.
I have a genuine WWII Collins #18 mini-machete (Marine Raider Bowie). It survived the Pacific theater conflict and only has some very minor pitting. That old Collins steel takes a razor edge. They were originally issued as survival knives for the US Army Air Corps in the 1930s. The current Case Bowie is a modern version in stainless. It just doesn't take the edge that the old Collins does.
