It would not matter how good security was.
Every weapon brought on those 4 aircraft were 100 percent legal. A knife shorter than 4 inches was untill today perfectly legal.
Cockpit access needs to be completely seperate from the main cabin. The pilots of cockpit were coerced into opening the door by the murder of the flight attendants. It is telling that they had to lure the pilots out of the cockpit. As much as we like deride the cockpit door as being able to be kicked in, that is not exactly true. It can be Kicked OUT, but not IN on an FAA door. The European doors were a different animal however...
Wino