Sorry if i made a confusing post. I think if you find "blue" in a description that is not specifically referring to Yasuki factory's aogami, then it isn't "blue paper"; usually it means "blued"
I extended the descriptive to include anything nearly similar such as calling Swedish plane making steel- blue steel. So the question is what alloy steel products were available during the period of straight razor production. Prior to 1920 or just a little earlier there probably wasn't any.