Hi,
Let me, with delay, congratulate you, Iain, to the sword. This is really nice piece (I mean the blade;, the handle (at least its surface), as it used to be, was changed/"renovated").
This discussion is very interesting. Concerning the iron used for the blades (as Colin put the question), I agree this is 100 % category c - forged in Africa from the iron smelted here. If you donīt mind, I will come back to my sword -
http://www.vikingsword.com/vb/showthread.php?t=12296 - as you can see. the lamination pattern is very strong, material is relatively dark (it is not possible to change the dark colour by polishing), the sword is relatively flexible (bent, but it is not possible to straighten it in hands). I did not see signs of corrosion.
Re other category of the iron used for the blades: Afars use steel leafs from old truck suspensions to make their jellys currently. The "simply" grind it (no forging now).
As far as corrosion is concerned, I would agree with Gavin, but maybe also temperature in connection with athmospheric pressure and dew point plays role. I seldom saw corodated jellys from Ogaden, but always bellawas from the Somali coast - both have leather sheaths.
Comming back to interesting fullers - it resembles me some Cameroon Grassland old spearheads, and also the central fuller on this Vere long sword (
http://www.vikingsword.com/vb/showthread.php?t=12730).
Regards,
Martin