“Seeing then that I will cut off from you the righteous and the wicked, therefore will my sword go forth out of its sheath against all flesh from the south to the north. And all flesh shall know that I Yahweh have drawn forth my sword out of its sheath. It shall not return any more.”
This time the judgment will be total and unrestrained. The whole land will be included, both those who think themselves righteous, as well as the very wicked. It will cover all, moving from the south upwards, and all will realise that this is indeed the work of Yahweh and that it is final. There comes a time for all when God's moment for reaping comes.
For ‘it shall not return any more' compare ‘it shall not be quenched' (Ezekiel 20:48). The two sections are parallel.