Yahweh continues to quote what the king of Assyria says. (See: Isaiah 10:8)
“Hand” here is a reference to military strength. AT: “As my powerful army has defeated” or “As I have conquered” (See: rc://en/ta/man/translate/figs-metonymy)
This refers to the king of Assyria.
During this time people believed that the greatness of an idol showed how powerful the kingdom that had built it was. The king of Assyria is saying that because the idols in Jerusalem are not as great as the idols of the kingdoms he has defeated, Jerusalem would be less able to defeat him than they were.
The word “Samaria” refers to the people who lived there, and “her” refers to the city of Samaria. Cities and nations were often spoken of as if they were women. AT: “just as I did to the people of Samaria and their worthless idols” (See: rc://en/ta/man/translate/figs-metonymy)
The king of Assyria used this question to emphasize the certainty that he will conquer the people of Jerusalem. AT: “I will certainly do the same to Jerusalem and her idols!” (See: rc://en/ta/man/translate/figs-rquestion)