Strong agreement with you, Cliff. Our society is being taught to always depend on 'the officials' to come protect them, yet I've heard of cases of waiting over 2 hours for police to come pick up a drugged up burglar that some citizens captured.
As for banning non-metallic knives, you'll never be able to stop people from figuring out a way around it. Plexiglass can take a nice edge...or real glass for that matter. Shoot, even a primitive obsidian knife can be sharper than just about any steel. You really can never stop it.