Fruitful. There is probably a play on words, the name Ephraim, by common derivation, being derived from a root meaning “to be fruitful” (see Gen. 49:22). The name Ephraim is commonly used in the OT as a designation for the northern part of the divided kingdom, because of the fact that Ephraim was the largest and most influential tribe in the north. In a similar way, the southern kingdom was commonly known as Judah, the most numerous and influential tribe in the south.
East wind. East winds in Palestine, coming from the desert, tended to be hot and scorching (see on Jer. 18:17). The mighty armies of Assyria are represented by this figure.
He shall spoil. Or, “it shall spoil,” that is, the east wind, although there is a sudden transition from the figure to the actual. It is the Assyrian conqueror who, coming from the East like a devastating east wind, would ravage and spoil Israel.