Hi Sid. This is indeed a very good question and a good subject for discussion. Unfortunately i cannot personally answer these questions. He is a link to a thread we had a while back showing some examples. Within that thread there is another link to a thread started by a person came to our forum because they were doing a research paper on these. I don't think they ever got back to us on their project or presented any final results.
http://vikingsword.com/vb/showthread...i+keris+holder