They call a knife like this a Manant, and in addition to being a weapon, it is also an adornment of prestige.
The Beja consist of 5 tribes, the Hadendoa being one of them.
They are descendants of the ancient Egyptians who were expelled from Egypt by the invading Nubians in the 8th century BC).
It would have been worn on the upper left arm underneath the robes.
The blades are often curved or asymmetrical, which makes this straight and artistically forged one most unusual.
The handle is ebony wood, and the embossed leather sheath also has snake skin.
Height: 10 ½" x Width: 2 ½"