The shaft has a diameter of about 1,4 cm (0,56 inches). I would call it 'semi-flexible', due to it's length.
In my opinion, it is a great throwing spear.
I once saw a film - I think the title is 'King Solomon's mines' - dating from the 1950's. The companion of the hero in this film was a very long African. At the end of the film, it seemed that this man was the rightful heir to the throne of the tribe they visited. The film shows a fight between the two princes. During that duel they use a spear and a shield, and also a slim sword.
Here are some more pics of the 'Ntore' dancers. These (and also the other two) were made in 1955 during the visit of the Belgian king.