I was stripping a hot ungrounded conductor while a 20A breaker was on by accident. When my wire strippers pierced the sheathing, a large spark blew out and tripped a breaker, but yet I felt nothing. There's a possibility that somehow that the hot wire got stripped AND the ground wire was touching the other end of my strippers and created a ground fault. I don't believe the ground wire was touching my strippers, but the idea of me creating a path for 20 amps to flow from my hand to the ground tells me that I wouldn't be here blabbing about this question. I just can't see how I wasn't shocked at all.
I've drawn out a highly realistic depiction of me on the day this happened. Please try not to get caught up on why things are the way they are and focus on the question at hand. There is a main breaker panel (grounded/bonded), then it feeds a sub panel (ungrounded / not bonded), and from there is where the circuit ends.