I found this piece last weekend at an antiques fair. The person who sold it to me is Congolese. He said it was from the Lega-tribe in North-East Congo.
At first sight it ressembles a 'mugishu' (or banana knife). This type of knife is found in the area round lake Tanganyika and lake Kivu (both sides of the border)
My new knife has a different shape and is better made then the other 'work' knives.
Here are some pics :