Not TSA, but the only time I've ever had anything confiscated was flying from Japan to NZ. They took my ~$15 pocket knife with it's 2.5 inch blade. But it turned out they gave it to the crew in a sealed bag because I got it back at the end of the flight. They did not however, once they'd confirmed the export paperwork was fine, do anything about the custom made ~$5000 iaido sword that I was carrying. So, 2.5 inch mostly blunt pocket knife, bad. ~4 foot razor sharp sword, perfectly fine.

I love Japan.