We'll see what the NCA has to say about this (National Cutlery Association).

This violates our civil right to "Keep and Bear Eating Utensiles"

Seriously, during hunting season, I have a knife on my belt almost constantly, and a 12 guage behind the seat of my truck. would I send my kid to school with a steak knife? HELL NO! Would I be pissed if a steak knife was used as a weapon at said school? HELL YES!
As a principal, would I have called police in this incident, with a child casually eating lunch? Probably not. A PENCIL can be just as deadly as a knife!

In most all cases of school violence, someone had seen or heard something that was not quite right, the "I'm gonna blow up the school" or "I'll kill you for that". These signs can no longer be taken lightly. In every case, the parent is ultimately responsible for the actions of their child.