‘Our redeemer, Yahweh of hosts is his name, the Holy One of Israel.'
But Who is this ‘I'. This interjected comment gives the answer. It is an indication of how Isaiah sees it. This judgment on Babylon will in fact deliver Israel from Babylon's unwanted attentions. Yahweh is acting as Israel's Redeemer. A ‘redeemer' was someone who paid up on behalf of a poor relative (Leviticus 25:25; Leviticus 25:48). So here Yahweh may be seen as acting on behalf of Israel, looked on as His poor relative, although it is only an interjection and secondary to the main gist of the passage.
The idea of redemption indicated delivery by the exercise of power (Genesis 48:16; Exodus 6:6). The basic meaning was delivering by the payment of a price; by the payment of money, the provision of a substitute or by the expending of power. We are not told which is the basic idea here. Possibly all three. The name ‘Yahweh of hosts' brings out that He is the God of battle and of all power. Thus His redemption will succeed. ‘The Holy One of Israel' is a reminder of His purity and grandeur (Isaiah 6:3). He is the unique and righteous One, and acts righteously against the unrighteous.