Answer:
There are millions of me. I am very small but when moving fast I am deadly.
What can be seen but never found that only hides in the unwound?
What do you use to hoe a row, slay a foe, and wring with woe?
Both punishment and sweet reward, It will befall both fool and lord. It is a spiritual scoreboard, Your every deed it does record.
I have legs but walk not, a strong back but work not. Two good arms but reach not. A seat but sit and tarry not.
Brings the sky a lot closer.