[tom hyle]

I'm not sure where the idea is coming from that this is an African/African-related style; it's pure European, (there are African Mediterranean dirks, but they're different; see "kodme") and other than the corvos and the pointed bolsters, any of these knives could very simply be from Itally or Spain. If they are from colonies they are pretty much straight copies.
I personally wouldn't read too much into pieces being originally sold with unsharp edges; it's a cultural thing that happens in various circumstances; it comes and goes; it is especially common with military blades, but not limitted to them. It seems to be an industrial cheapskating/streamlining. The persistance of nonsharpness while owned by natives does something to say these are mostly vestigial/symbollic in modern times, as expected.
The type is a dagger-knife used for work, hunting, and self-defence. Usually in thrusting the pommel is placed against the palm, as with many guardless knives.
The "pen type" clip is a fairly old and traditional European thing. Some sturdy versions on swords (on guard or sheath), firearms, and axes will be on the back side, but most commonly it is on the front side of the sheath on blade weapons, and you can figure it out from there; the knife is worn thrust thru the belt with the clip engaged to the belt to keep it from sliding out. Sometimes these go with a "frog" but those are more usually "buttons" than clips. This type of clip has been popular on daggers (including "bowie knives") in the Americas, but is also popular in (for instance) Sicilly and Corsica (ie the former Kingdom of the two Sicillies).