A warrior will deploy every intelligence gathering tool available to him meticulously, in search of the weakness of his enemy so he can exploit it favourably. In warfare, all is fair, provided the victory is won. Thus, the exploitation of the enemy's weakness is a valid strategy. David saw that metal protection covered every part of Goliath's body except his forehead, and aimed at that spot! Don't forget scriptures describes some warriors as, "Among all these were 700 chosen left-handed men; every one could sling stones at a hair and not miss" (Judges 20:16). David was of the category of warriors who never misses.
Another critical instinct of a warrior, is that he doesn't get involved in 'civilian affairs.' Paul puts it this way, "No man that warreth entangleth himself with the affairs of this life; that he may please him who hath chosen him to be a soldier" (2 Tim. 2:4). You've been enlisted into God's army and the army for the survival of your destiny and all those who are connected to your purpose. You better stay off distractions and anything that could entangle and put you in a blind spot or on the line of fire. Learn from Samson; avoid becoming a cheap casualty; stay away from entanglements.