They have always been dark. Not entirely sure the exact process. I always thought parkerized.
In the 90’s there was a model made. it came in a white box with the blue print art work printed on it. It was meant to be a representation of a ww2 knife. The coating on it is very dark, and rough almost porous. I think it is parkerized.
The ww2 knives are lighter and smoother. I don’t know if it is from wear and oil, or if it was different.
The new ones are painted or coated definitely not parkerized.
Parkerizing and bluing are chemical processes closer to patina than paint.