I think he's an NCO of the 11° Régiment de Ligne-re or the 11° Régiment de Forteresse.
His medals:
1. Military Decoration for Long Service
2. The Commemorative Medal of the Reign of Leopold II
3. The Industrial and Agricultural Decoration gold
4. The Industrial and Agricultural Decoration silver
5. Medal of the Royal Federation of the ex-NCO's of the Belgian Army
It's possible, that he's a mobilized reservist in the first days of the Great War?
Also very hard to find Belgian Congo ,military items, before 1908/1910 when Congo was privately owned by Leopold III.
Many Scandinavians volunteered to serve in Afrika for Leopold III.
One can see here an (originally Norwegian!!) Belgian officer holding his sword.
Here is a similar sword to the one he is holding, I have different manufacturer's.