Since the Bible says that on Judgment Day, which follows the millennium and is not during it, would be of those both righteous and unrighteous, we presume that those killed at Armgeddon wiill return on Judgment Day. In that case, no one technically undergoes the "second death" to Hades until Judmgent Day. All those killed before Judgment Day are in Hades, the common grave, which means they are coming back.
As far as "spiritual death" goes. A spiritual death is presumed for the prodigal son while he was away from his father's house and living a life of sin:
Hello JC,
During the Millenium satan is in prison and not allowed to mislead the nations. Judgment Day is when Jesus Christ returns correct? The second death has no resurrection whereas the first death does. Which man upon the earth will not repent once they see Jesus Christ arrive in all of his glory? Which missiles will they choose to use against the son of God?