Answer:
I help engines spin and pants stay up.
I am gentle enough to soothe your skin light enough to fly in the sky and strong enough to crack rocks.
I am all around yet to me you are half blind. Sunlight makes me invisible and difficult to find.
Against the sun I protect your eyes and am often worn on the face of spies
I am the beginning of eternity the end of time and space the beginning of every end the end of every place.
I am rarely touched but often held. If you are smart you'll use me well. What am I?