Moses said to Joshua, “Choose some of our men and go out to fight the Amalekites. Tomorrow I will stand on top of the hill with the staff of God in my hands.”
So Joshua fought the Amalekites as Moses had ordered, and Moses, Aaron and Hur went to the top of the hill. As long as Moses held up his hands, the Israelites were winning, but whenever he lowered his hands, the Amalekites were winning. When Moses’ hands grew tired, they took a stone and put it under him and he sat on it. Aaron and Hur held his hands up—one on one side, one on the other—so that his hands remained steady till sunset. So Joshua overcame the Amalekite army with the sword. Ex. 17:9-13
Just thinking of Moses doing this makes me wonder if I could do what he did for very long. The use of the staff reminds me of the staff Moses used earlier in Exodus that turned into a snake, an ordinary object God made into one of His wonders. However, I think two other things are going on here.
First, the holding of his hands is a way of praying to God. It is nonverbal communication. I will at times use my hands in gesture to God, especially when I want to acknowledge something He did for me. You see football players doing this after a touchdown. This is body language.
Second, Joshua's troops, battling the Amalekites, could look up on the hill and see Moses in this pose. It was a reminder that victory rested in God. The swings in their fortunes coincided with the non-verbal "prayer" of Moses, with Aaron and Hur in supporting roles. More prayer, more results.
I don't think it wrong to have activities that remind us of God's ability to work on our behalf. "In all your ways acknowledge Him" goes Prov. 3:6. As long as we don't vest supernatural power in the object or activity, we should be OK.