The worst cut I ever got from a folding knife was from a Kershaw Blur (tanto).
This was back in college, when I was first getting into knives and the mall-ninjary still had me under its spell. I was surfing the web and enjoying the AO -- much to the chagrin of my suitemates. Eventually, I had to get up to check on the food I was cooking in the kitchen. As I stood, I fumbled the knife as I tried to close it and it fell on my foot. I wasn't paying close attention but I felt the impact. I thought that a hammer dropped on my big toe and looked down. No blood on my white sock. I assumed that the handle struck my foot and I shuffled off to check on dinner.
As I returned to my desk, I was checking some emails and could feel a slight throb in my toe. I ignored it, however. Then I felt like my toe was wet and I assumed that I had spilled some water on my foot while I was in the kitchen. Finally, it dawned on me that the sock was getting wetter not drier. I looked down and saw that a large, wet blood stain was covering the tip of my sock.
The tip of the knife had entered so cleanly that the bleeding was delayed. The cut was small but pretty deep. I couldn't get the bleeding to fully stop until the next day. Even then, I had to go to work and the cut would open up while I was on shift. This headache lasted for two weeks, just as I was preparing for my graduation. So yes, I had to resort to walking like I had a peg leg in order to keep the toe stable and allow the cut to close. That was the last assisted opener knife I ever bought and will likely ever own again.