Although no steel is truly rust proof, the addition of 13% chromium in an alloy the chromium will bond with itself forming a film that will reduce oxidation. Often, the more chromium content, the lower the performance of the steel.
30-40 years ago, one could say with a good degree of accuracy that stainless steels were not as good as non-stainless carbon steels. Stainless steel would be harder to sharpen, not get as sharp and dull quicker. These days, there are many good stainless steels which offer good edge formation, edge life and sharpenability.