Thank you all for your educated opinions and I agree with the most of you (sorry Tim
) everything by this knife let me think Nias as well. And I think and hope that it is the real deal.
The patina of the brass handle is IMVHO the give away, thank you Robert for lighten up the picture, it show it much better.
Kai, be sure that I will show better pictures soon.
So by length it is a Si Euli, see by the handle style in Albert G. Van Zonneveld, page 123, pic. 498.
Thank you all again,
Detlef