Use vinegar to clean the rust, leave the blade in the vinegar (the normal one, not big deal) overnight, in the morning wash it with a lil of baking soda, or if this doesn’t work (when theres a lot of rust) rub the blade with a damp piece of very fine grade emery paper, followed by rubbing it with a slice of onion, rinse well with hot water and dry it with a soft cloth.