What not to bring on an airplane in your carry on

You'd think I'd know the answer to this given all the flights I've been on. But the following story would suggest otherwise.
Dave and I flew up to the North Island two weekends ago to see our friend Chris perform in Whagarei's production Miss Saigon. As we went through the Christchurch security gate, the security guy asked if they could scan my purse again. I of course said sure, and they ran it through again. I had cleaned out my purse that morning so I was fairly confident of all its contents. After the second scan an ancient old security guard asks me if he could look through my purse. Again, I say sure. After a few moments he said, "I'm sorry Miss. I just can't seem to find what was coming up on the scan." I then think maybe it is my inhaler, tucked away in a mesh bag. I said, "Oh, I know what it might be. Here". I take out the mesh bag, unzip and immediately see my foolish mistake.
See this mesh bag is one I use for hiking. I keep it close by as my emergency bag, something that can be easily accessed. It has my inhalers in it as well as a knife. I forgot about the knife when I put the mesh bag in my purse. So when I unzip the mesh bag and see the knife I know exactly what the ancient security guard was looking for. I pull out the knife and said, "Is this what you were looking for?" And he looks at me like I am crazy. I hand him over the knife, and he unfolds it. It is a decent sized knife. The knife is slightly rusty but still very sharp. I just shake my head and say, "take it, take it. I know I'm so silly." I don't even try and argue about keeping it. He apologizes and says I can't take it on the plane. Of course I can't take it on the plane!!!
Dave and I walk away chuckling at the thought of my trying to smuggle at knife on the airplane. Then I stop in my tracks and think to myself, "wait a minute." I pull out my mesh bag and open it up. Knife number two was in the mesh bag. This was a knife my sister had given me. But because I was the one that pulled out knife number one, the security guard didn't see the other knife. Oops!
We didn't have any checked luggage so I had to leave that other knife up in Northland. It will be mailed back to me sometime soon. Lesson learned.
By the way, 4 weeks left.