A rod of iron is a shepherds tool. Shepherds have two sticks, one is a crooked staff the other an iron rod.

The staff is used to separate one animal out of the flock. The reasons can be quite different, such as to treat the animal for some malady or milk them, or they are what’s for dinner. The iron rod is rarely used.

Sheep are not at all shy of predators, making them vulnerable to attack. To keep the sheep safe, shepherds strive to keep the animals together so a careful eye can be kept on them. When an animal wanders away from the flock, it must be immediately found.

If it is still alive and well, it must be taught not to leave the flock. The shepherd takes the rod and breaks the back leg. The lame animal must now be carried to water and to grazing. It becomes completely dependent on the shepherd for all its needs. After it heals, it will never leave the shepherd’s side again.

“You shall break them with a rod of iron, and dash them in pieces like a potter’s vessel.” Psalms 2:9

. . . but with righteousness he shall judge the poor, and decide with equity for the meek of the earth; and he shall smite the earth with the rod of his mouth, and with the breath of his lips he shall slay the wicked. Isaiah 11:4

. . . and he shall rule them with a rod of iron, as when earthen pots are broken in pieces, even as I myself have received power from my Father; Revelation 2:27

From his mouth issues a sharp sword with which to smite the nations, and he will rule them with a rod of iron; he will tread the wine press of the fury of the wrath of God the Almighty. Revelation 19:15

The Good Shepherd is about to teach the nations to never leave His side.