The Japanese spent 1000 years learning how to preserve bare steel (usually after it had been drenched in blood) and their method is basically as follows. They used oil of cloves or oil of camellia as the rust preventive and a powder called uchika as an abrasive. Near as I can tell, uchika is very finely powdered pumice stone, somewhere on the order of 3000 grit. The sword was already polished so the samural only needed to preserve it. The oil was applied, the dust pounced on with some kind of puff ball, then coarse paper was wrapped around the blade and pulled forward from tang to tip. The blade was wiped with a very soft cloth and reoiled. A freshly polished blade needed to have this done every few days but once the oil started leaving a residue, it was only required once or twice a year (excepting exposure to regular combat). You might try oil of cloves as a traditional rust preventive - it was likely around in the 18th century.