If you know yourself, then you can head off big mistakes. When you know your own weaknesses and strengths you are better able to appraise a situation and make better decisions about the tasks you are facing. If you know that you aren't great at handling details then you will know in advance that you need to enlist a detail-oriented person to help you accomplish a task full of little pieces. Acknowledging the weakness enables you to recognize and avoid potential pitfalls to achieve a greater chance of success.
Knowing yourself enables you to protect yourself and others. I know that when I have been in situations full of sensory stimulation and social interaction then I am going to reach a point of overload. When that happens I am more likely to become irritable and it becomes difficult for me to think clearly in situations that require my attention. I just don't have enough emotional energy left. I have learned to recognize when I am reaching my limits and to plan some quiet times for recharging. This puts me in a better frame of mind to handle the necessary intricacies of personal interactions and decision-making and protects others from the negative effects of my weakness.
Knowing yourself enables you to make better choices and have a more effective impact. When you see your own strengths and weaknesses clearly, when you know what motivates you or triggers a meltdown, you can make choices that maximize your ability to accomplish God's purpose for your life. You will be able to put supports around your weaknesses- people to help you, guidelines to protect you- and make way for your strengths in a way that enables maximimum impact and effectiveness. It isn't a lack of faith to acknowledge and protect weakness. It is a recognition that God built us with weaknesses so that we would recognize our need for Him and His wisdom, and our need for others. We are designed for interconnection, with God and with people.
Know yourself and maximize your God-given potential.