John Gill Commentary Ezekiel 31:17

"They also went down into Sheol with him unto them that are slain by the sword; yea, they that were his arm, [that] dwelt under his shadow in the midst of the nations." — Ezekiel 31:17 (ASV)

They also went down to hell with him To the grave with him; many of his nobles, princes, generals, soldiers, and subjects:

unto them that be slain with the sword ; to be buried and lie with them who had fallen by the sword, as a just punishment for their iniquities:

and they that were his arm ; either that leaned on his arm, were dependents upon him; or his ministers, his instruments, whom he employed under him as his deputies, to govern the several provinces that belonged to him; or rather his allies and auxiliaries, who helped and assisted him on occasion:

that dwelt under his shadow in the midst of the Heathen ; in the midst of the nations subject to the Assyrian empire; such who put themselves under the protection of it, lived comfortably under it, and continued with it to the last; these shared the same fate as that did.

The Targum is, "his governors are broken, whom he strengthened in the midst of the kingdom."