African Tribal Arm dagger .... possibly WW2 ?

[katana]

Hi all,
bought this very cheaply...believing it to be 'tourist grade'. On receiving it, the very rusty blade was indeed thin (approx. 2mm) yet seemed highly tempered (with very little flex, with fairly sharp edges.)
Some wire wool and a little effort revealed a guality steel blade with the number '4' stamped on it (both sides of the blade and in the same place).
The blade under magnification shows file marks to shape the blade and possibily laminations in the metal structure.
The handle seems to be composed of horn or similar material, it feels 'plasticky' and is warm to the touch but the 'hot pin' test does not give that burnt plastic smell The creamy white 'rings' are some sort of hard plastic which has become age hardened and seems quite old. The 'pommel' is missing I have no idea whether the original was shaped like a Baja hilt or had the more familiar 'disc'.

The construction overall is 'good or better' quality. Where the blade came from...I have no idea.....but I am getting the notion that perhaps this was manufactured WW2 era. Perhaps a modified military blade. I don't think this was made from a machete because the blade is to thin (the stamped '4' either side suggests this was the original thickness)

If anyone has any ideas...or similar examples I would be grateful for your input.