Uwe, the blade needs to be polished so the hada is not readily visible and the finer activity in the hamon is also not visible. You say it's not a real nihonto, I must disagree. Given the characteristics, it bares all the signs of a Bizen school blade, The shape of the nakago and the patina, the sori, the shape of the kissaki, and lastly the type of hamon all point to a Bizen school blade most likely Sue-Bizen. These are but a few points that tell me it's a real sword. Granted I have been away from collecting for a few years and that even with my 40 plus years of studying nihonto I any still a novice. But at this point I think I know a real Japanese sword from a cheap fake or Chinese knock off.
I was think I might buy some nugui polish and do a small window at the ha-machi. I intend to send this for polish at some point so it IMO wouldn't do any damage to the blade.
I appreciate your comments.