Like Hoss, I grew up with all knives being in the low to mid Rc50's hardness. You sharpened them with a file and any abrasive thing around. Every kitchen had the required washer type sharpened. It shaved off steel along the edge like a bastard file on mild steel. We sharpened knives while camping on a rock and stropped them on our boots or belt.
Knives were sharpened at much higher angles than today o make the edge last a little longer. If you went for a lower angle the wire created was a big problem to get rid of.
One noticeable thing back then - The wire from sharpening was really a large projection from the edge, because the steel was so soft. You could flip it back and forth with your fingers.
When I made my first knives in the 60's, good steel was whatever I could find that would harden. When a knife was finished, I thought it was the hardest things on earth. I water quenched, forge tempered, and probably hit Rc55-57. There was no real way to know the actual hardness back then, and to tell the truth, I didn't even know that there was a measurement system for hardness. My only use of the words rock and well was dropping a rock in a well to see how deep it was.
By the mid 70's a commercial knife was around Rc57. When I went back to knifemaking in the late 1990's, I hardened to around Rc58-59, like everyone else did. Now my soft blades are Rc-59-61, and chef blades are 62-63-64.
Part of this is the far better steels available today, but much is better HT and understanding of metallurgy. Hobby and custom knifemakers now use HT ovens, proper conditioning of the steel prior to quench, and accurate tempering ... plus actually measuring the hardness.
Re-reading my post makes me feel really old. I mention an open dug well (don't see those anymore), found steel being the best source, young kids having knives, sharpening knives with files and pull-through sharpeners, and not knowing any metallurgy or what hardness really was. That would seem like caveman technology to todays knifemakers.
Funny (not so funny to me at the time) memory from this:
In 1959, I was getting ready to go camping with dad and his scout troop for the first time. I wasn't a Boy Scout yet, but went to the meetings with dad and had spent lots of time in the woods and camping as a family. He was letting me come along as a mascot. I had my gear packed early Friday morning and decided to make sure my pocket knife was sharp. I pulled it through the kitchen hand-held washer sharpener a few times ... and the last pull it dropped across my thumb. It sliced to the bone. Mom had to take me to the navy base hospital and four stitches. We got back with plenty of time to meet dad and the troop at the church. I went to get my gear and was told that I couldn't go for fear of getting an infection. I was so bummed. I made the best of it by pitching the tent in the back yard and spending the weekend outside. To this day you can still see the place where I cut that thumb.
Larrin
states that this steel has almost no carbide so it highly benefits from hardness increases. 
