Unless you talking about a blade with real corrosion and pitting in it I've found that products like Simichrome or cape cod polishing cloths do a really fine job of taking off minor rust and gunk and really polishing up a dull blade. The cape cod cloths have more abrasive in them and can do more wwith minor corrosion or more rust. They can also be used to polish up the scales if their either plastic or celluloid.