Well, we all know that the crews are not to be trusted flying a multimillion dollar jet around full of passengers.
It's absolutely CRUCIAL that the people at the controls of said plane not be permitted to bring on board a personal steak knife identical to those included with first-class food service. They might do something DANGEROUS with it!
(For those inclined to wonder, a passenger-jet pilot on FlyerTalk's forum a few years back told of being stopped for just such an "offense". He was allowed to "surrender" the knife and continue on through security to get to and fly the plane without further incident.
Miraculously, the plane made it to its destination without issue.)