[tom hyle]

The original question, read carefully, and as further explained, seems to me to refer to a lesser, tighter defined, group of weapons, BTW, than what we've all proceeded to address, which is fine and dandy by me, but just pointing it out. There are edged weapons that are purely ceremonial (etc.); some of us just feel that many get improperly lumped into this category. There are two common reasons for this mislumping that I'm aware of: 1/ the lightness and thin-ness of many blades seems unfightingly flimsy to the modern N American, including most modern N American martial artists. But it seems to me that the fact of the matter is the African of the past often preferred a fast, unwearying, light blade, whose thin-ness will cut right to the bone on a good, well-made cut. 2/ Some have features that may seem useless, etc. when you think of modern European style academic sword ("sword"?) fighting ("fighting"?) where there is no sheild, and the sword is used for parrying (I believe the real existance of this style outside sport/training and formal duels is highly questionable; all I read points to Europeans ceasing to make sheilds, but continuing to use them, and even deliberately carry them, in the form of other objects; gloves, lanterns, capes, and hats have all been designed specifically as sheilds, but I digress; imagine!). But in traditional Africa (as with old Europe; the rest of the old, "true" if you will, "West") you fight with shields, and some shapes are especially designed for that. The 'Zande mambele I've mentioned (which is much larger and more curved than the Fang/Koto rank marker [?] one we've been shown) are such a sword. They are for reaching around shields with. I rarely meet an American who can grasp their proper use, so foreign to the fighting styles popular/respected in N America, and in a way that's a good thing, which brings me to another point I've wanted to make about having odd weapons; the enemy can't grab them from you and instantly competently use them against you. Sure, if he takes them home and has time to study them, he'll likely either figure them out or make something else from the metal, but I mean, actually in the fight (and this has to do with some sheath designs, too; ask a N Plains American Indian why their traditional knife sheath takes in most of the handle; that's the reason they cite; it makes it hard for your enemy to grab your knife and use it against you; it keeps it in place when you're climbing, riding, etc. too, but that's not what they go right to to explain it....).
Just to complicate matters though, I've seen a fair bit of armour in traditional African settings. Ashante soldiers in chainmail (ditto Somali soldiers), Sudannic cavalry in quilted armour (much more effective than one might think, especially when you remember they used fibres that were especially hard to cut on purpose), an Akan-seeming soldier fetish wearing similar quilted armour. The existance of armour that will stop sword X though in no way implies sword X was not for fighting within that same culture at that same time; the PURPOSE of armour is to protect you; it does its job, and by no means every weapon is designed to deal with it, and it's a tough nut to crack, even with a weapon made to pierce it.
A .32 gun in the pocket ("for fun; he keep a razor in his shoe....") will not pierce any decent body armour (or a 'phone book); it's certainly still a weapon; a very viable, and even common, weapon in modern N American culture.