I'm awake. Just formulating my response.[8D]

About the guy getting hit in the head, he's still alive because nobody has ever shot an arrow that was completely stablized as it left the bow. I bet that arrow doubled up as if flexed when hitting his skull.[:-]

As soon as the arrow leaves it's power source, wind resistance starts slowing the arrow down, draining off it's speed, energy and momentum (though the higher the momentum, the more speed and energy the arrow retains). The arrow doesn't have all it's energy and momentum established in the same line until it has stabilized it's flight.