This is a MONGO shield attribute to the NGATA.
Semi-large type called gube.
Yours seems to have a clear part in the middle part : some shields are covered in the center with another plaited part to reinforce the front.
See the pictures at the bottom...
I don't think you need to repair it, just clean it.
Yes, this kind of shield was used for war.
"The most often used material for wickerwork comes from the central vein (rachis) of the leaves of different palm trees (elaïs, borassus, piassava,raphia...)" GUBA Ivan Baur Africa shields Vol I
Well done they are strong enough to protect from arrows, some spears, throwing knife and they are especially light for close-combat.
Yours is a nice one, they are not easy to find in good state, and cost a lot, even in Belgium where we can find some.
The rarest are the ZANDE shields, shorter, nicest one, and very expensive.
I have the "big" model of Mongo:
http://lulef.free.fr/html/mongo.html
Luc