Answer:
Used on a diamond and left on a board. It's great for a gymnast his grip to restore. What is it?
I am so simple that I can only point. Yet I guide men all over the world.
They try to beat me, they try in vain. And when I win, I end the pain.
This is in a realm of true and in a realm false, but you experience me as you turn and toss.
The weapon of choice to create the biggest shock.
What covers its face with its hands, speaks no language, yet most known what it's saying?