This kind of insanity annoys me... Apart from anything else in todays climate of fear regarding the possibility of someone attempting to hijack a plane and crash it in to something or someone I suspect that one wouldn't be able to successfully hijack a plane if allowed to get on board with a 9mm pistol and a hunting knife. The fact is that one (or even 10) person (people), no matter how well armed is fairly unlikely to be able take on several hundred airline passengers who are entirely convinced that they will die if they fail to stop the person.
Or at the very least they shouldn't be able to. Logic would suggest that it should be very hard to frighten people into submission when submission means certain death and fighting back means just the possibility (and unless they have a gun not a particularly great probability) of death or serious injury. In a one on 200-300 or so fight, even in the cramped space of a cabin I don't give the one guy much of a chance of even causing any serious injuries, rock or no rock...
Maybe I play too many strategy games and am too used to the idea of acceptable casualties but I'll happily be the first to tackle the terrorist with the box cutter if it means not getting smashed into a building, blown up and incinerated, I know which I'm more likely to survive...