The name Joab means "God is father," and it was ultimately only to God that this tragic hero could turn for support. Joab is a classic example of a man whose strength as a warrior was also his fatal flaw. When Joab saw someone whom he thought needed killing, he did not hesitate. Thus, he murdered Abner and Amasa against David's wishes, thinking he was eliminating a threat both to himself and to David.
On the other hand, Joab evidences an important quality that David sometimes lacked in his willingness to confront threats, even from members of his own family. While one does not normally think of David as weak or indecisive, the story of his relationship with Joab reveals how Joab intervened several times to bring David out of a depression that literally endangered the kingdom. The narrative also reveals that Joab, though impulsive at times, possessed great wisdom himself in the use of "wise women" to achieve important goals that men could never accomplish.
Joab also deserves credit for many of the military victories normally associated with David. His act of delaying the capture of Rabbah in order to allow David the honor shows not only his loyalty to David, but also his wisdom in avoiding a situation in which David might—like Saul before him—grow jealous and suspect Joab as a threat to his own power. Joab's capture of Jerusalem, his defeat of Israel's national enemies, and his leadership in putting down the rebellions of Absalom and Sheba show that he was literally the power that helped give David his throne and kept him seated on it.
Reverend Sun Myung Moon says that "Jesus comes in place of David. Thus, he was supposed to work out his mission centering on King David's 40 years."  In that sense, Joab can been seen as a type of "formation stage" disciple who loyally protected the "anointed one" of God, even though he went too far in doing so at times.
In the end, Joab was a victim of his own sin
, murdered at the orders of his cousin, King Solomon
, just as Joab himself had murdered his own cousin, Amasa. The scene of his assassination, clinging to the horns of the altar in the tent of Yahweh
, is unforgettable. The king and uncle whom he had loyally and effectively supported throughout his life had betrayed him on his death-bed, and Joab could only cling helplessly to God. However, even the sanctuary of God's altar could not protect in the final moment. Shakespeare
himself could not have conceived a more fitting end for the hero of this classic tragic drama.