A very nice dagger, Flavio.
I believe that the Holbein-ish t-grip shape of the grip indicates an origin from Cameroon rather than the Sudan. We had a discussion about this style of dagger on the "old" forum a year or so back, but I couldn't find the discussion quickly using the Archive search.
Here's a more recent (and more touristy!) version of a Cameroon dagger:
