These knives are Eritrean and most notable from being collected during the Eritrea Mission organized by the Italian Ministry of Education in 1905 and 1906. I think that they can also be found into Eastern / North- Eastern Sudan. Here are two from my collection. The links provided show more detailed references at the bottom that I have gathered about them.
https://www.the-mansfield-collection...ritrean-dagger
https://www.the-mansfield-collection...rean-dagger-57
-Geoffrey