If your concerned about having a backup blade in a PSK there are upgrades. The natural first thought is a small folder. In the past we've seen small SAKs, Douk Douks etc. Another option I mentioned in an old thread was a blade blank with a rattail tang. Some are small enough to fit diagonally in a tin or you may sacrifice part of the tang for greater blade length. You will have to improvise a handle, but it's a quantum step up. My friend Ragnar @ www.ragweedforge.com has a nice selection at moderate cost.