Basically if you have to wonder whether the TSA will hassle you for trying to bring X onto a plane, the answer is that they will.

As for types of knives, about the least scary knife anyone can possibly imagine is those plastic throwaway ones that you get in fast food places. And among those, there's the relatively solid ones, and the really cheap flimsy ones that snap in two if you look at them the wrong way. I had one of the flimsy ones in my backpack for some reason and the TSA confiscated it and threw it away.

Basically, whatever it is that you want to bring aboard, put it into a checked bag instead, or mail it to your destination ahead of time.