The Maasai 'seme' swords and the so named lion hunting spears (moran) are fascinating ethnographic weapons, and very much so from the complexity of the history of these tribes they are attributed to.
I have a pair of the moran spears I acquired about40 years ago which somehow never really properly researched nor catalogued (no photos either) along with a shield I believe reasonably modern. You have inspired me to see if I can get to these
The spears have quite long blades with pronounced central rib, and it seems the blade is about the same length as the haft. If I have understood correctly the ribbed blades, much as on the swords indicate older period ('old' typically 1900-1930). Earlier examples (very old are pre 1900).
From historic and anthropological points, the study of the Maasai is both intriguing and complex. There are many misunderstandings about the lion hunting etc. and the fact that they are primarily a cattle herding nation.
Apparently in the late 19th c. disease epidemics decimated the Maasai tribes as well as the rinderpest virus killing up to 90% of the cattle. Without getting into colonial issues etc. the reason I noted this is toward the dynamics involved in trying to date these weapons.
As a British protectorate from 1935-1955 there were ordinances prohibiting the metalworking etc. so I wonder if this had anything to do with the blades becoming those from reworked machetes (Martingale Co. in England).