tn The line here is very difficult. The Hebrew text has כִּי־יָד עַל־כֵּס יָהּ (ki yad ’al kes yah, “for a hand on the throne of Yah”). If the word is “throne” (and it is not usually spelled like this), then it would mean Moses’ hand was extended to the throne of God, showing either intercession or source of power. It could not be turned to mean that the hand of Yah was taking an oath to destroy the Amalekites. The LXX took the same letters, but apparently saw the last four (כסיה) as a verbal form; it reads “with a secret hand.” Most scholars have simply assumed that the text is wrong, and כֵּס should be emended to נֵס (nes) to fit the name, for this is the pattern of naming in the OT with popular etymologies—some motif of the name must be found in the sentiment. This would then read, “My hand on the banner of Yah.” It would be an expression signifying that the banner, the staff of God, should ever be ready at hand when the Israelites fight the Amalekites again.
sn The message of this short narrative, then, concerns the power of God to protect his people. The account includes the difficulty, the victory, and the commemoration. The victory must be retained in memory by the commemoration. So the expositional idea could focus on that: The people of God must recognize (both for engaging in warfare and for praise afterward) that victory comes only with the power of God. In the NT the issue is even more urgent, because the warfare is spiritual—believers do not wrestle against flesh and blood. So only God’s power will bring victory.