DD,
It is my understanding that Shaka, had the shafts (metal) of Assengai (and I think other types of spears) lenghened. This allowed the spear to be withdrawn more easily and quickly from the unfortunate victim. In battle- conditions this was important ....a spear quickly withdrawn was ready for the next opponent.
The second spear certainly looks to be the earlier style because of the shorter shaft....and therefore quite possibly old. I say 'possibly' because again these could be faked. However, IMHO yours looks to be genuine.
I have an Assengai, which was made pre 1964, I suspect its '40's - '50's, it too seems machine finished. Very similar to the blade in your picture.It is well made and well balanced but obviously hasn't the 'aura' of an original spear. I would say it is a 'replica' and it originated in S Africa.
Going back to the extruded bar: Many African countries were purchasing old equipment/machinery from Europe etc. after WW2 .It is possible that it was extruded from old foundry equipment but using 'modern' steel.
I am sure there are others on the forum whom have much greater knowledge than I, hopefully they will add to the thread.
I forgot to mention, many have been 'fooled' at some time or other, especially on eBay. But sometimes, I feel, you have to take risks ....nothing ventured... nothing gained.
I think the important thing is that you learn from these mistakes................
