Answer:
Scythe of darkness, Shadow’s light. Guiding eye of thirteenth sight.
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.
You seek it out, when your hunger is ripe. It sits on four legs, and smokes a pipe.
What can be heard and caught but never seen?
Two people are born at the same moment, but they don't have the same birthdays. How could this be?
I have two eyes in the front and a lot of eyes on my tail