If you gotta have it, buy it before it is banned. Kinda like the old surplus spring launched blades that hit in the late 80's....of course now they are a felony to own and, to the best of my knowledge, was never granted amnesty. There are things called bang sticks if you want a defensive weapon while diving, giving you a much better reach vs Mr. Sharkie....
As far as hunting goes, am I wrong to suggest that a firearm at range trumps a contact range stabbing with a burst of air? I think not.....
Tactical knife? Maybe if you are a Navy Seal and need to dispose of a sentry silently.....then again the guys have been using knives, tomahawks and any/everything else they could get their hands on, seems to have worked so far, so I doubt if they need the gimmick.....
All in all gimmicky crapola that will no doubt be misused by rednecks while swilling copious ammounts of beer (no offence to any righteous "good ole boys", who should not be confused with the less desirable redneck) or criminal elements. Not to mention all the mall-ninja's will have to own one.
-Bill Liptak