Hello!
I have corresponded with Marie-Christine Heinze who has investigated Yemeni Jambiya for her doctoral thesis. She provided me with the following two reports.
The German Jambiya Expert
The Yemeni janbiya and its various parts
I have also found this document by Esther van Pragg to be very interesting and useful (skip to page 17):
Introduction to the world of old silver jewellery from the Land of the Queen of Sheba
Please let me know if you have trouble accessing the documents!
Best Regards,
Dave A.