I am not so sure that these daggers originated with the Rumbek Jur .....these two knives have similarities to each other...but not to 'ours'
http://southernsudan.prm.ox.ac.uk/details/1930.86.11/
http://southernsudan.prm.ox.ac.uk/details/1930.86.12/
Kronckew, I have seen a number of these daggers (straight and curved) without a scabbard, and assumed that they were originally part of a 'set' (of 3)..yours is the first I have seen with its own sheath. (perhaps a later 'addition'...

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