Re: One pilot's opinion
First, passengers should throw stuff, anything at the hijackers. It's quite distracting. :)
Then, I suggest that passengers inventory their studiest pens and car keys. Keys raked across the face are not fun.
Also, use your blankets and coats as devices to throw over the faces & heads of hijackers. That pretty much spoils their response to your attack.
I heard a hostage advisor say that the very best thing you can do in any such situation is anything and everything that disrupts the scenario the hijackers had planned. Throws their timeline off and puts them off their game.
-philw