David's administration is set up: Joab is army commander, Zadok and Ahimelech are priests, Benaiah heads the bodyguard.
David shows kindness to Saul's family, restoring grandson Mephibosheth to his lands, and giving him a place at his table forever.
How this is about Jesus
He is subduing the nations to Himself even now (Rev. 19:11, 15).
He rules His kingdom through church, families, and the state.
He has shown kindness to us like David did to Mephibosheth. We were in the house of his enemy, but he favors us and provides for us forever, though we are spiritually lame and cannot provide for ourselves or get away from His justice.
David is not only strong, but wise and kind. A leader needs all three of these to succeed.
Those who know they have received mercy, will be merciful (Matthew 18:21-35).