Sforno on Exodus 4:17/ספורנו על שמות ד׳:י״ז

1ואת המטה הזה, even though this staff is not made from a particularly valuable type of wood I have sanctified it to serve as a sign for you. תקח בידך, as a symbol of authority to demonstrate that I have appointed you to change the rules of nature at your command.

2אשר תעשה בו את האותות, which you will command nature at My command, seeing that you have been appointed by Me for this task.