I believe the warriors carried what they liked or had.
The iklwa was the favoured weapon but the knobkerrie was popular as well - if a warrior had one - the would probably carry it.
Fighting sticks were a tradition weapon amongst the Zulus, from a young age. Iklwa's were generally not allowed in the presence of the king - that is why when it all kicked off with the uThulwana and inGobamakoshi - they started off clubbing each other until one side ran to their camp to arm themselves with sharper weapons and it all broke loose.
The knobkerrie was seen as a weapon of mercy (or so I have read) and was used to put friends out of their misery, execute 'criminals' etc.
As for the throwing spears it really depended on how big his hands were and how many he owned - myself I wouldn't see it being more than one or two (if at all) - remember the Zulus had no 'baggage' train and had to carry everything themselves (leaving aside the udibi boys) - imagine carrying a shield, maybe a musket, a stabbing spear, a couple of throwing spears, a knobkerrie and snuff spoon.
The Zulus were a tribal culture and had no Regulations as to what to carry.
About the best answer I can give - sorry not be more precise