As we've seen, to be poised for something is to be ready to do it, as if you're standing still, or sitting still, about to begin at any moment.
But "poise" is also a quality you can have. If you have poise, you hold yourself in a steady, graceful state of balance and preparation. Here's a musician with poise. See how confident and ready she stands! Her back is straight, and her mind is focused.