Thank you very much for your answers.
Hmm ... I will say frankly that he considered the possibility that it might be a razor to shave. But I found nothing similar. I compared this to the old blade razors: Spanish, generally European, Egyptian, Chinese - nothing.
I am a passionate about Spanish Navajas and according to me (although I'm not an expert), it is not Spanish Navaja de afeitar. Of course I have no confidence.
Still, after all, does not exclude the possibility that it could be razor. Only that it probably does not come from the Iberian peninsula. I was looking for razors now in Arabic, Serbian, Croatian, Bulgarian, Turkish... - also nothing.
The blade is not unique. Many knives Europe (and elsewhere) has a similar blade, it's not special. The key role of the handle, which is very rare. Especially the ending. Here is the key to the puzzle. I also saw a razor, with a similar blade, but the handles were very different. Their handles are curved or straight, but did not have such a "tail".
I hope I hit on the right track.
Bardzo dziękuję.
Janusz