Origin of the term Eisenhauer

[Dmitry]

This blade inscription often appears on Solingen-made blades of the second half of the 1800s. Eisenhauer, i.e. an 'iron-cutter' marked blades indicated a particularly high quality [nothing more than a marketing trick, in my opinion].
However, I have seen at least two blades marked Eisenhauer, which, at least in their appearance, may date well prior to the 1850s. What is the earliest example of the blade marked Eisenhauer that you have seen?