interesting. i'd assume that it is fairly rare. i looked carefully at the business end where a spike would have been in the popup enlargement, did not see any damage where the bone spike would have been attached and broken off. will of course look hard when it arrives. if it is in fact a woomera, that's not too shabby, they're not a dime a dozen either. if it's a sword club, even better to me. similar but more elaborate sword clubs are used in the pacific oceanic islands flat but edged profile, and have been noted in the history books as capable of hacking and removing limbs. you do not need to be especially sharp to do that. tho it helps.
a fairly dull edge still concentrates the force of a blow that might not otherwise break bones.
the attached photo of a similarly carved woomera shows the tit on the end where the spike would be. i gather the cross section of the woomera were not necessarily symmetrical about both axis like a sword, so i'll be looking for that too.