Ouch.
Maintenance is also a factor. I have a lockback folder that I've been carrying for fifteen years. Recently, I noticed that the lock didn't lock, which could potentially be dangerous. The company still makes the same model, so I bought a replacement. Then I had an epiphany, and looked more closely. Sure enough, the space the blade opens into was packed with fifteem years of pocket lint, which prevented the last couple of degrees of opening rotation that allowed the lock to snap into position. I cleaned out the lint, and it now works as it's supposed to.
