there are literally hundreds of steels that can be used for blades, O1 is only used because it is cheap, easy to find in small precision ground pieces and StMears has his early ones made from it.
Some will resist patination better, but the blade finish makes a big difference even with the same steel (for example my forged finished O1 blades look the same yeas after manufacture, but the satin finished look different and so do the polished ones). Steels should be chosen for other qualities such as resistance to wear and shock, how fine the edge will get too or toothyness, then ease or method of manufacture, etc.
Silver Steel (BS1407) holds a better edge than O1 and doesn't rust quite as much. 52100 likewise and is tougher, so does cs80crv2. Other steels that aren't as good edge holding but tougher than O1 include EN42, cs70cr, EN9/EN43, EN11, cs70. They are just the ones that I use. 15n20 (or 75ni8) have a bit of nickel and are often used for the bright layer in pattern welded blades, so will resist corrosion better than O1, it is a spring steel of 0.7-0.8% carbon and very tough, but only found in thin section (I have it in about 1.6mm).
If you are after semi stainless and good edge holding then you are looking at D2, D6, etc. They are not really forgable and require pretty special heat treat but are very good steels that can be found relatively easily from the various metal sellers. Similarly A2 I believe is fairly rust resistant as well as a great tool steel, again heat teat issue for home use.
I would give up on West Yorks though. They list every steel under the sun, hold very little in stock and charge a fortune for it! Try Argent, Barmond or Furnival, much cheaper, have good ranges of steel and are very helpful.
Are you looking to make something yourself, or is this just academic interest? If you plan to make then how are you going to make the blade and what sort of kit do you have? It might have a bearing on which steels are better for you
