Here is a good meditation on the scene in Prince Caspian when, though seemingly alone, Lucy willingly stands to fight because of the presence of, and her trust in, Aslan (go to his post and you can watch the moving movie clip):
We all know that a little girl with her dagger is no match for the onslaught of an oncoming army. But still, Lucy does what must be done, trusting that, even though she didn’t see Him as she stepped out on to the bridge, Aslan would make things right. Lucy was well aware of her weakness, reminding us of Paul’s startling declaration: “when I am weak, then I am strong” (2 Corinthians 12:10).
Truly, I say to you, unless you turn and become like children, you will never enter the kingdom of heaven (Matthew 18:3)