I don't understand. What does two totally ignored blades have to do with sharpening blades as part of a regular maintenance?
I have two blades for my mower. The one that is on it, and a spare which I sharpen when it comes off the mower, so I can put a sharp blade on whenever I need. The original is 10 years old, and the spare is 9 years old. Neither look anything like the pictures posted by the OP. Both still have factory black paint on them in most areas, and where metal shows, it is shiny. Even after 9-10 years of use and sharpening, they still have plenty of material left. In fact, a visual inspection would reveal only to the most experienced of us that the blades are as old as they are. And they still balance well.
I suspect these two blades came from a mower that has not only always been left outdoors, but parked over something that has constantly been moist.