Hello Russel,
Interesting theory.
I don't think that these knives are necesarrily fake because they are offered cheap.
Here is another thread on these weapons.
http://www.vikingsword.com/vb/showth...=turkana+wrist
You can see pictures where the knive is worn completely surounding the wrist, but also pictures where it is sort of half around the wrist/hand near the thumb.
Best regards,
Willem