The razor itself won't rust (unless wildly abused or neglected). Think of the razor like the fixtures and faucets in your shower. They're finished for corrosion protection. Light care will go a long way for their longevity. Shaving blades (of any variety, from safety razor blades to cartridge blades) will eventually start tarnishing. Water + Metal + Time = Rust, eventually. Keep your blades dry between uses for their longest life. And swap them if they need it. If a blade stains the razor body with rust, simply scrub the razor to remove it.