"In that day the Lord Almighty will be a glorious crown, a beautiful wreath for the remnant of his people." NIV translation
Isaiah compares the crown of Samaria which was destroyed by the Assyrians with the crown of Jesus Christ. We are reminded that the phrase "in that day" is a technical term that refers to the Great Tribulation, the Millennial Reign, and eternity afterward.
We are also reminded of the fact that Isaiah was a prophet that was sent to the people of Judah and Jerusalem. With this in mind, we see that he is reminding the people of the example of the northern kingdom and the judgment that came upon them as well as the fact that a remnant remained.
He is reminding the people that, even out of that bunch, there will be some who are saved in the end to reign with Him. This would have been a message of hope to the people of Judah as they were facing judgment as well.
For us it shows that there is hope for us no matter what religion we have become tangled in. If we dump all of the "religious" stuff and just accept the finished work of Jesus Christ, we can rule and reign with Him.
"He will be a spirit of justice to the one who sits in judgment, a source of strength to those who turn back the battle at the gate." NIV translation
The "He" speaks of Jesus Christ and we see that He will pronounce a sentence on those who hold onto religion but He will give those who reject their teaching and trust in Him the strength to win the fight. The Hebrew word that is translated here as "spirit" is "ruwach" and it can be translated as "breath" in the sense of proclaiming a verdict or judgment. The phrase "one who sits in judgment" or "yashab 'al mishpat" refers to those that reject His words. The phrase "those who turn back the battle at the gate" or "shuwb milchamah sha'ar" speaks of those who stop fighting and turn towards a gate. This speaks of those who turn away from their own efforts at repairing their relationship with God and accept the way to a right relationship which is through Jesus Christ.