David was raised up as God's new leader for His people. Saul gave David his royal armor to wear:
Then Saul dressed David in his own tunic. He put a coat of armor on him and a bronze helmet on his head. David fastened on his sword over the tunic and tried walking around, because he was not used to them. "I cannot go in these," he said to Saul, "because I am not used to them." So he took them off.
2 potential lessons for leaders:
1) Seek fresh vision from God. Avoid the temptation of copy-and-paste visioneering. Embrace change and transitions. God always gives fresh vision to new leaders He raises up. If He had wanted things to remain status quo, He would have left Saul in charge.
2) Don't allow past milestones to hold back a prevailing future. If David had "done it the way its always been done," he would have clumsily fallen down. The old way of doing things (the former vision) did not fit his unique style of leadership. Instead, this young new leader did what needed to be done at this moment in Israel's history: by faith he moved forward confidently in a fresh new direction.