The last people on plane to have guns should be the air marshalls. Given them a decent few weeks of close combat, takedown, and restraining first. Have some good old prison guards teach it.
Right now only two things define an air marshall: a stamped badge and a popgun. None of them will make it to retirement -- they'll either go nuts or have a blood clot or heart attack that kills them in a few years. No one can ride hours on hours in airline seats and stay healthy. The job is 99.995% utter boredom -- we'll see more of this sporadic self-assertion on their parts, not less, as they each get closer to the ragged edge of nutanity.
These guys are undercover right? I was thinking the other day that they might be the ones in danger. If someone pulls a gun how does a passenger know they are who they say they are? If someone with a gun flashes a badge and tells passengers to sit down and keep their seat belts on what are they supposed to do? Didn't the terrorists have fake IDs?