2 Samuel - Power and Presence

I used to think the "Sopranos" on HBO was about as violent and vindictive as you could get, but that was before reading about bloody general Joab who is constantly tossing someone's head over a wall or impaling them with a spear, or Solomon's favorite "hit man," Benaiah. All of these stories make me wonder whether or not it's possible to have human power and to trust in God. Does our sense of personal power get in the way of trusting God's power? David and Solomon seem to balance the two somewhat successfully with some notable exceptions. But on the whole, it seems like a pretty shaky alliance. Are all of these stories just supposed to cure us of our desires to reach the top? What does it mean to, "Be all you can be"?