The pax are a much neglected resource in a hijack, shoe bomb, air rage situation.
That said,
proper training and information rather than how to do surgical operations with a soft drink can would be more appropriate as you may be a smoking hole in the ground by the time you have hand crafted your weapon <img src="frown.gif" border="0">
Human wave tactics will save the day. Seat cushions make good shields against tweezers, knitting needles, leathermans etc. Seat belt buckles can be used if numbers are short.
Hijack resistance tactics should be part of the pre-flight safety briefing and should be on the seat back safety cards.
It is sad that a mentally disturbed young person suffocated after being piled upon by passengers, but the bad guys need to know that immediately they try something on a a/c, that's what may well happen to them.
Alert and switched on pax will turn out to be a far stronger deterrent to terrorists than all the pious embargoes and procedures that pass for security these days.