Hi Roanoa,
nice collection......I too have reservations as to these being Zulu...the spears seem to have Zulu characteristics, the binding for example, but their overall shape and design is 'different' to most Zulu spears I have seen.
The mace is great

but I never seen this type attributed to the Zulu either. As you and Lew have pointed out. and DD hinted at...a neighbouring tribe seems likely....so the Shona could well the originators.
There is, I suppose, a possibility of some of these weapons could have been traded or adapted (from 'war trophies') Which, if were 'collected' from the Zulu and would have had thier origins 'elsewhere'.
Irrespective of all that........very ...VERY nice additions to anyone's collection