Answer:
Thousands lay up gold within this house, But no man made it. Spears past counting guard this house, But no man wards it.
Creatures of power, creatures of grade, creatures of beauty, creatures of strength. As for their lives, they set everything's pace. For all things must come to live. Under their emerald embraceย Either in their life or in their death.
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.
Not a burden for its weight and daily carried out, He who takes it wishes it had never come about
Talks like this, a green wise man does. Guess my clue, you will.
I am rarely touched but often held. If you are smart you'll use me well. What am I?