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Thank you Andrzej! Yes, I was referring to this picture.

By the way I own the dagger that belonged to Mr. O'Brien and I believe this is the dagger that can be seen on the first picture, see...

This is because he is wearing Imperial Russian uniform on this picture.

The gentleman on this picture is Colonel Patryk O'Brien de Lacy who was the head of Technical Research Armored Arms Bureau (B.B.T. Br.Panc.) in Warsaw.
Full biography of O'Brien de Lacy can be...