I think a ball-point pen is more dangerous than a blunt knife that you might get with a meal.
There are so many other threats:
Break a wine bottle, use jagged edges/pieces
Strangle people with belts
Throw laptop batteries upside peoples heads (ouch!)
Bring power supplies to electronics and whip them around fast by the cord and release with aim
Our only defense is to use the seat cushion as a shield...