I've got a knife just like that, although the etch on mine is not as bright as yours. I use a drop of simi-chrome on a small buffing wheel attached to a roto tool to remove stains on blades. If you are careful and go lightly you can the stains and leave no evidence that thet were ever there.
Boker has quite a history. I would refer you to, Goins' Encyclopedia of Cutlery Markings. It appears that there were several Boker companies. Boker USA, is dated 1917-1986.
I seem to recall reading (though I can't remember where) that Boker USA was started during World War I when the company who were importing German Bokers could no longer do so because of the war.
According to Goins, the Boker name goes back into the 1700s. In 1986 Heinr. Boker Co. of Germany bought Boker USA. "Boker Cutlery USA is the import agency for the German company."
See Goins, 1998 edition, page 28 and 29.
I hope this helps.
As a side note, I have several Bokers, some from Germany, some USA Bokers, at least one made in Argentina and one or two that were made in China (unbeknownst to me when I bought them). I would have to say they are all decent quality knives, though I prefer not to buy the ones from China.
Boker makes a very good knife. My favorites are the older german bokers, the early USA bokers are good too. I won't buy any from argentina or china. I have a hawkbill identical to yours on the way right now, once I get it and do some research I'll let you know what I find out.
I only have three Bokers (not counting a couple of Chinese ones). I have a drawer queen given to me by a friend. A beautiful drop point folder with full blade etching, brass bolsters and rosewood scales. He was going through a very tough time in his life and was contemplating suicide in a very serious way, so he began giving his most prized knives to his best friends. I began sticking very close to him, giving him encouragement to "keep on keepin' on". He finally made it over the hump, but I wasn't about to give the knife back to him!
"This ain't Dodge City....and you ain't Bill Hickock!"