Obviously this thread caught some interest so I will contact him on Sunday and ask him to join this discussion so you get his arguments directly from him.
I don't know any marin biologist myself but if there is one on the list, or a member knows one good enough, maybe you can ask him for a comment too?
Unfortunately it isn't that easy to walk around with a large head hunter sword in central Stockholm and draw the blade among 100's of people inside the natural history museum during the tourist season without getting trouble with the police.
On the use of human bones I have never seen or heard about it being used for mandau hilts, unlike skulls placed under the main pillars of the long houses. Probably because of that it doesn't match the Dayak belief system.
On transit hassles fortunately there are no customs between EU-countries (Sweden - UK). Otherwise it might be a problem even if I have never experienced it myself as I only buy blades from before the ban.
Michael