The plain Hebrew of Exodus 17:11 says Moses lifted his hands, and when he did, Israel prevailed. What were the raised hands actually doing? The Targum Pseudo-Jonathan leaves no room for confusion: "And it was, when Moses lifted up his hands in prayer, that the house of Israel prevailed; and when he rested his hand from praying, that the house of Amalek prevailed."
The Aramaic inserts the word prayer twice, because there was a real danger that readers might imagine the raised hands themselves had power — that Moses was some battlefield sorcerer pointing the rod and collecting victories. That reading would miss everything.
The Mishnah in Rosh Hashanah 3:8 makes the same point with a question: "Do the hands of Moses make war or break war?" And answers: no — when Israel looked upward and directed their hearts to their Father in heaven, they prevailed. Otherwise, they fell.
The Targum is making that rabbinic insight native to the verse itself. The hands were a signal flag for prayer, a visible pulley that pulled the nation's gaze up. The moment Moses's arms dropped, the connection broke and Amalek surged. The takeaway: even the most gifted leader's prayer is finite, which is why leaders need support. It is also why the battle against Amalek, in every generation, is fought on the knees first and with the sword second.