Isaiah 59:16 KJV
16 And he saw that there was no man, and wondered that there was no intercessor: therefore his arm brought salvation unto him; and his righteousness, it sustained him
Who is the antecedent of him in the above text?
The previous proper noun is "LORD" in v15b. This forms the antecedent for the several verses that follow. This includes the Isa 15:17 which provides the background for Eph 6:10-17 and the armour of God.
Ellicott comments on isa 19:15b:
And the Lord saw it . . .--The verse at first suggests the thought that what Jehovah saw were the sins thus described. The sequence of thought, however, tends to the conclusion that the words are properly the beginning of a new section, and that the supplied pronoun refers to the repentance and confession of the people. It displeased Him--literally, was evil in His eyes--that the penitents were still subject to oppression, that they found no leader and deliverer, and therefore He came, as it were, alone and unaided, to the rescue. (Comp. Joel 2:17-19.)
In the next verse, v16, the Pulpit Commentary suggests:
He saw that there was no man, and wondered that there was no intercessor; i.e. God looked for some champion of the oppressed to arise; it was to be expected under the circumstances. But, alas! "there was no man." None stood up to resist the unrighteous and protect the innocent; much less did any stand up to deliver Israel from its heathen adversaries. When it is said that God "wondered" at no champion appearing, we must understand the expression as an anthropomorphism· Therefore his arm brought salvation unto him. As them was no human champion, it became necessary that God should arise in his own Person, and show himself. "His arm" and "his righteousness" were enough; no human aid was needed, or could have added anything to the resistless strength of his might (comp. Isaiah 63:5).