Sudanese (?) crocodile sheathed triple dagger set with Arabic script

[katana]

Originally Posted by VANDOO

YOUR EXAMPLE IS INTERESTING IN THAT IT MAY HAVE ACTUALLY BEEN USED NOT JUST SOLD TO A TOURIST, IF THE REPAIR TO THE MIDDLE DAGGER HANDLE IS A NATIVE REPAIR IT MAY HAVE BEEN CARRIED AT SOME TIME. IT ALSO APPEARS ONE HANDLE HAD TO BE REPLACED AS IT DOSEN'T MATCH THE OTHER TWO.

By what I can tell, the repair is very old and definately looks 'native'. The knives are sturdy and still fairly sharp, doubled edged on the straight dagger and single on the curved versions. The Islamic script is 'worn' which suggests that the knives have been removed/replaced in the sheath on many , many occasions.. They 'feel' used....the handle of one is slightly larger, interestingly the blade in this one is lose, ....suggesting replacement?
How can I identify the handle material i.e bone or horn?