Here is some pretty easy steps I found a while back on how to remove rust I had a similar problem with a Old Case Knife I had lost but found it in my basement and had rust spots on the blade... Hope these tips can be of some use for you...
Step 1 Remove any residue or dirt from your knife by cleaning with a soft cloth or a soft-bristled toothbrush. Use a lightweight oil as lubricant. Do not use water as this will encourage further rust.
Step 2 Remove any remaining rust spots by applying a good coat of oil and allowing the knife to set for several days. Wipe the knife clean with a soft cloth. If rust remains, gently scrape the rust spots with a clean, sharp knife. Work carefully to remove only the rust, leaving the original blade undamaged.
Step 3 Apply another coat of oil, and work it in well with a soft cloth. Wipe off any excess oil, leaving a thin coat of oil to protect the blade.
Step 4 Remove stubborn rust deposits with white vinegar. Soak a soft cloth in full-strength white vinegar, and apply to the blade. You may need to let the blade set with the cloth on it for a while for severe rust buildup. Scrub gently with the cloth or a soft-bristled toothbrush, and rinse with clear water. Throughly dry the blade, and coat with oil to prevent further damage.
Step 5 Try an old home remedy by inserting the blade of your pocket knife into a raw potato and letting it set overnight. Remove the knife, and clean with a soft cloth or toothbrush. Rinse and dry thoroughly. Apply a coat of oil.
Step 6 Clean the blade with lemon juice to loosen and dissolve the rust. Saturate a cloth with full-strength lemon juice, and apply to the knife. Let the knife set for 15 minutes with the blade wrapped in the saturated cloth. Scrub clean. Rinse and throughly dry your knife. Apply a coat of oil to protect the blade.