Got hit twice, once back in the late 60's and then mid 90's. Right thump 2nd joint and left last time, same place (matching scars). Drove myself to E.R. Dr. chewed me out good for driving myself. I was in shock. Had to wash the drivers side of my van next day (you guess why).
Nothing more permanent than scars. Got very lucky.
I now make very sure the aircraft or test stand is very securely prevented from any forward movement. I move very slowly and very deliberately, even exaggerated motions when ever I connect power to the engine (wide and away from engine and prop arc). I try to maintain total awareness of were my right hand is and put my left behind me as soon as I can.
I Now always use a chicken stick. or a good leather glove with a Kevlar glove inside of it, or an electric starter. (Kevlar glove also very useful when carving parts). Xacto blades will do incredible damage to you.
But the real danger actually starts when that motor starts.

And no more out alone. Slice an artery and you could bleed to death.