Hi OsobistGB,
I can't really help you much with this dagger, only share some thoughts.
First, this is NOT a standard military issue dagger because theses are highly...standartized=all look the same, and carry the same stamps denoting their origin. See the attached pictures for a very good example from Artzi's collection.
These daggers are very popular an fetch very high prices at auctions, so there are plenty of immitations as well. But then again, yours does not look like an immitation, even if you consider the possibility that the scabbard is a later replacement. So, this could be a Special Award Dagger for Ottoman Officers, but only people who know such daggers can tell you that..
