
Goliath wasn't the only giant David ever faced, years after Goliath's death, a descendant of Goliath attacked David. This time David was weak and exhausted and was not able to face his giant alone, Abishai, David's nephew came and killed this giant for David.
We all face giants in our lives and maybe even have kill those giants, but like a bad zombie movie sequel they come back to attack. Giants may represent sin or a problem that we may have had the victory over and thought we would never have to face again. David was known as a giant killer so it would surprise an outsider that he was unable to fight this battle, but Abishai as David's nephew would have seen David the man, not David the giant killer and realized that David was indeed human and at times weak and it was in his weakness that God used, not his strength. This gave Abishai the courage to face this giant in confidence that even though he was human like his uncle David maybe he too could slay this giant. Abishai had never fought a giant before but he had seen David have the victory so he had the courage to take on the giant and protect David during his weakest moment. Abishai learned from being in the house of David from being in communion with him and having seen what he did made him able to do the same.
As believers sometimes our victories are for ourselves and sometimes they are for others to witness and emulate. When we are weak and our giant returns, like David we need our closest friends to help fight our battle. Sometimes our weakness is an opportunity for others to step up and carry us giving them authority and strength they didn't have. This requires us to be weak and vulnerable, something men often don't want to be in front of other men. But in our vulnerability, friendships are strengthened and victory can be ours.
It was Abishai's ability to kill Ishibenob that enabled others to have victory over the giants. Up until David, no one had killed a giant, but after Abishai killed his giant, several others (Sibbecai, Elanan, and Jonathan) are credited as having killed giants. I would argue that if David had defeated this second giant, David's reputation would have increase as a giant killer but no one else would have been able to kill a giant. But in Abishai's victory, others realize that the power David had was not exclusive but was something that was available to anyone who believed.
David's inability to fight this giant is a great example of how we can't always rely on our leader's to fight our battle's for us. We have to learn from their example, grab our sword and slay our giants because YOU CAN.