Yahweh bares His arm so that the nations can see the “salvation of our God” (Isaiah 52:10; Heb. yeshu’at-elohenu). The genitive seems obviously to refer to the salvation that God brings. After all, what sense would it make to speak of God Himself being saved?
But then Isaiah twice writes of the Lord’s arm that brings “salvation to Him” (59:16; Heb. tosha’ lo) and “salvation to Me” (63:5; Heb. tosha’ li). Those phrases are not wholly unambiguous. We might translate those phrases as “salvation for Yahweh” and gloss them as “the salvation that Yahweh brings to pass for Israel.” But why the circumlocution? Why not stick with the genitive?
Suppose we bite the bullet and say that Isaiah is talking about Yahweh bringing about His own salvation. What might that mean?
Perhaps something like this:
Yahweh has bound Himself to Israel, given them promises and a hope. He has so bound Himself that His own reputation as God depends on the fulfillment of those promises. He puts His reputation at risk by binding Himself to this people. His name depends on what happens to Israel, and Yahweh’s name is His presence and character. If He abandons His people, then it’s only reasonable to conclude that He is not the God He claims to be. He will prove Himself God only if He bares His arm to restore Israel and to establish righteousness.
The salvation of Israel is thus simultaneously the salvation of Yahweh, the salvaging of His own reputation and His own name.
And, in the event, this happens in the Father’s rescue of the incarnate Son from the grave, for in the resurrection God bares His arm to save God.