After various threads on the so called 'sword fish' swords and whether they were actually used by natives or were 'made-up' inventions for the tourist trade. I found this on eBay, knowing that sharks teeth are generally quite sharp, usually with serated cutting edges, I would imagine that this weapon could cause serious injury to an opponent, especially with 'slashing' styled strikes. (Once a shark has bitten into its prey, they shake their heads from side to side, this causes the flesh to be cut by the cutting serations on either side of the teeth...)
http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA%3AIT&rd=1