The following are online citations from Moshe Chafetz's 1710 work Melekhet Machashevet, found on the internet.
Not all links are still active, but relevant text is excerpted here in full.
Excerpt: "Behold I will strike the water... with the stick that is in my hand" (7:17).
The Egyptians worshipped the River Nile, as is well-known. Chazal have said, R. Moshe Cheifetz quotes a Gemara in Avodah-Zarah (45), that it was customary to place a stick in their idol's hand, a hint that it ruled over the entire world. That explains why Moshe told Paroh that he would strike the Nile 'with the stick in his hand', as if to say 'See who is holding the stick!'
For more information: The Chafetz Project
Any and all information about Melekhet Machashevet or Moshe Chafetz is greatly appreciated.
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