The third person in the scenario is Saul. Saul is the person who should have gone to confront Goliath. He was tallest in the kingdom, he had weapons and armour and in theory should have been a skilled warrior by that time.
Saul in fact had become 'Mr. Dithers'. When the nation needed leadership Saul was nowhere to be found. His only plan to defeat Goliath was to offer his daughter and tax free living to the family of the man who would defeat Goliath. Creative on the one hand, tremendously disappointing on the other. This could have been Saul's greatest moment but Saul had lost 'it' and so it became his undoing.
If you were to flip back a few chapters, you would see the moment Saul lost 'it'. Saul's life is a study in leadership gone wrong. It's a picture of a man called to the top but lacking the character and discipline to stay there. What should have been the begining of a dynasty became a one throne disaster. Saul's problem was pride and independence. Saul would not follow God's instructions or meet his expectations. He did not understand roles and responsibilities. He couldn't figure out where he should be and where he shouldn't be. At the end of the day it cost him the kingdom (position) and more importantly God's presence and power (ore the anointing) in his life.
Saul was anointed as the king of Israel but the anoiniting went to his head and resulted in a train wreck. It's not uncommon today either. When the anointing moves from your heart to your head, a disaster always follows. When the anointing goes to your head, your perspectives change and you begin to function from the place of entitlement and privilege rather than from the place of a servant.
Lost anointing leads to indecisiveness and incompotence and eventually it catches up to you. Saul was so lost in himself that even after 6 weeks of daily challenge from Goliath, he couldn't figure out what to do next.
Pride and independence make it impossible to rise to the challenge of the giants. I've finally begun to understand that the reason God hates our pride and independence is because it comes between Him and us. It also causes us to live at a level far lower than what God intended for us. Jesus said that apart from Him, we can do nothing. I'm not sure how it works for out for you, but I know that every time I do it my way when I know I could do it God's way, a mess always results.
Saul's pride cost him everything. What does yours cost you?