Thank you, Gentlemen, for your insights.
I have a friend who served in the (U.S.) Peace Corps in Tanzania in the mid 1960s and he brought back a Masai spear - very much like the newer example in my initial photo - purchased in downtown Dar es Salaam along with shield. A friend had asked him to bring back a set and he bought his own set at the same time. I'll opine that these were 'facultative' as tourist items - that is, something still made mostly for the local market - rather than "obligate" such as the three or so very degenerate examples I recently saw at the same flea market diminished in scale to fit into luggage and also something without impressive workmanship.
The newer one in my photo came cheaply from a local auction. I have another of the same form - an early purchase on my part - that was all forged to shape but which had been dulled and chrome plated. That one is actually hanging up along with a number of other early acquisitions of quite variable quality. I cannot manage a panoply either, more from architectural than social restrictions, but I have two 'braces' for my overflow of spears - one for African and the other for Asian.
That image from Thomson's book could be the same spear
The dealer indicated that it had been from a museum deaccession, with no further details, but well worth the $100.