Answer:
I cost no money to use, or conscious effort to take part of. And as far as you can see, there is nothing to me. But without me, you are dead.
Known to accessorize with feathers, trumpets, and harps.
What is long and slim, works in light. Has but one eye, and an awful bite?
An iron horse with a flaxen tail. The faster the horse runs, the shorter his tail becomes.
With pointed fangs it sits in wait. With piercing force it doles out fate, over bloodless victims proclaiming its might. Eternally joining in a single bite.
I have two eyes in the front and a lot of eyes on my tail
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?