Now (literally forever): This phrase points to ongoing consequences. It stands in contrast to God’s gracious promises of a lasting kingdom that God gave to David earlier (2 Samuel 7:13–29).
This is a reminder of what David did with the sword (2 Samuel 12:9) and how the sword would affect his family. This recalls David's careless reaction to Joab's report about the deaths of Uriah and other innocent Israelites (2 Samuel 11:25).