Sometimes, just letting a fine coating of rust form and then oiling it will give the same effect. This way you will have an "old Russetting" effect that will make a sword look old and by applying the light oil will keep it from rusting further. Acting as an extra deterrent.
We just received a letter from a former Park Ranger that used to wear/use a rapier, crossbow and archer's salade we made for the Cabrillo National Monument in demostrations. These were made 20 years ago and the Rapier hilt had turned a beautiful antique "plum" color over the years. Originally, it was polished and then given a heat blueing that gave a purple/blue hue. The photos on our website give you some idea.
Sometimes, just the passage of time is best.