There's a distinctive sound made when a prop cuts in to fingers or other body parts. I've heard it a few times too many, that's for sure. Personally, I've never actually been cut by a prop, but like it was mentioned above, I've had fingers knocked away from the back of the prop several times. It smarts, but it's never been a problem.

I definatly wouldn't go trying to knock the glow clip off the engine with a stick. You don't know which way that thing is going to bounce, but I'd put money on "in to the prop" as the most likely direction. At that point, you've got something fairly hard going in to the spinning prop, and it's going to come out moving pretty fast, going somewhere it shouldn't . Never mind the parts of the broken prop.