Light surface rust can be removed with Maas. I define light surface rust as no pitting of the underlying blade. Once you get pits, the whole game changes. You can also use one of those flexible fiberglass pads that 3M makes and judiciously clean off the rust. Sometimes a stain will remain. That's patina and we all get it as we age.

Be really careful to hold the blade so you don't cut yourself while de-rusting.