I´d put it in a waterproof pouch or at least a ziplock bag. You can coat it with oil (I use Break Free CLP similar ocassions) but this would be messy and files don´t work well with it. If it gets wet make sure to dry it completely. If your wave has a leather sheath don´t put it there while the sheath is still wet. I treated the sheath of my wave with warm vaseline so it doesn´t get soaked with water anymore.

BTW: Spec sheets for "stainless steel" tell that you will loose a certain amount of steel in a specified environment due to corrosion and that there is no pitting corrosion. They don´t claim that it´s rustfree .