Come on guys, arming pilots is not the solution. Before long we will be arming bus drivers and train conductors!
The solution is to stop these people before they get near the aircraft.
However, if someone does get onboard and decides to start some thing then lets face it, we all have a duty to take control of our own destiny. If someone stands up and starts a problem they should find themselves faced with a number of angry pax. Let's not just sit there like terrified sheep and be led to the slaughter.
The cockpit door should stay closed regardless of what goes on in the cabin, land at the nearest airfield and if you are somewhere that precludes this, then dump the cabin pressure. Running around is a bit more difficult if you don't have any O2 or you have a mask stuck to your face.
Something else to be considered should be an ID card for someone in a uniform such as Police/Military/Fireman etc.. They could identify themselves to the cabin crew as someone to be counted on during a problem. The reward for this is a discounted airfare ,but they would not be allowed to drink alcohol on the flight.
The old idea of "let's just do what they say and we will all be OK" no longer applies. It is now"you do something and I will stand up and kick your @ss or die in the attempt."
I owe my wife and child nothing short of that or I am a pathetic excuse of a man.