For years, I've packed a good knife in a hidden pocket of my toiletries kit in my checked bag. Get my bag, retrieve the knife in the nearest restroom, and I'm good to go. At least now I don't have to dismantle my keychain to fly. I keep a Victorinox mini SAK on my keys. Use the scissors and nail file more that the two blades, but at least I could cut something like a hangnail waiting for a flight.