I'm assuming we're talking etching the blade in ferric, then applying the "mark" via elctro-chem etch. I suppose a person could do both at once using some type of resist for the "mark"....but in my experience that usually ends up looking like a cat's behind.
Any way it's done, (etching the blade AND etching a "mark" there will be issues to overcome. That's one of the reasons I choose to hot stamp most everything.....it eliminates most issues when it comes to etching, coatings, etc. The only time I use an etched mark is when the stamped mark is unsuitable..... like very thin blades, or those that are left machine or hand finished and no etching or coatings.