I use Hoppe's gun oil, Outers gun oil, and RemOil on my guns. Breakfree works well too. Any quality gun oil would probably work. Use an old t'shirt or soft rag and rub lightly. For places where rust has built up pretty thick, you can use 0000 steel wool (some use brass wool) with the oil to clean the worst build up of rust. I have done this for years on modern handguns, antique handguns, and swords, and if done correctly, will not remove any original bluing or patina. Again, do NOT rub aggressively and go slow. Finally, do NOT polish the brass handguard, just use the oil. Some feel that polishing the brass makes the saber look better-big mistake! Good luck.