Just a quick thought....the metal 'spiral' could be a zinc alloy. Africans are masters of utilising any resource. They obtain the zinc alloy from the outer casing of dry cell batteries. (invented late 19th C).
Bearing in mind many areas are fairly remote from electrical supplies, the use of batteries by colonalists was increasingly more widespread as the 20th C progressed. Discharged batteries were not re-chargeable and discarded.
A fairly similar sword from Africa
http://www.vikingsword.com/vb/showth...ghlight=toureg
Regards David
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