The rod was the gat, the heater and the staff was the trusted lieutenants who carried out the boss's orders.

Or, conversely, there was an old English tradition of using two words to translate one if the sense of the word in the source language didn't quite match the sense of any one word in the target language.

Or, perhaps the two words meant totally different things to a Jacobian English speaker. The rod being a rod of authority and the staff a shepherd's crook. The Luther version gives Stecken (stick) und Stab (crosier) and the Segond ta houlette (walking-stick) et ton bāton (shepherd's crook). The Vulgate doesn't seem to match up at all near as I can tell, the 22nd nor the 24th neither.