Answer:
I am the tool, for inspiring many. Buy me in the store, for not much more than a penny. Don't overuse me, or my usefulness will go.
What zips through the sky with a tail of fire and dust. It could be an omen, its origin to discuss?
Though desert men once called me God, today men call me mad. For I wag my tail when I am angry. And growl when I am glad.
I am free for the taking. Through all of your life, though given but once at birth. I am less than nothing in weight, but will fell the strongest of you if held.
I follow the orders of only two. I respect the work of only two. I am in constant battles with many, Though one surpassed them all. With forces joined, We created hell, Until our mutual enemy fell. Who am I?
You use it between your head and your toes, the more it works the thinner it grows.