Read this excerpt about the Vietnam War from "Ambush" by Tim O'Brien: When she was nine, my daughter Kathleen asked if I had ever killed anyone. She knew about the war; she knew I'd been a soldier. "You keep writing war stories," she said, "so I guess you must've killed somebody." It was a difficult moment, but I did what seemed right, which was to say, "Of course not," and then to take her onto my lap and hold her for a while. Someday, I hope, she'll ask again. But here I want to pretend she's a grown-up. I want to tell her exactly what happened, or what I remember happening, and then I want to say to her that as a little girl she was absolutely right. This is why I keep writing war stories:

He was a short, slender young man of about twenty. I was afraid of him-afraid of something-and as he passed me on the trail I threw a grenade that exploded at his feet and killed him. . . .

Even now I haven't finished sorting it out. Sometimes I forgive myself, other times I don't. In the ordinary hours of life I try not to dwell on it, but now and then, when I'm reading a newspaper or just sitting alone in a room, I'll look up and see the young man coming out of the morning fog. I'll watch him walk toward me, his shoulders slightly stooped, his head cocked to the side, and he'll pass within a few yards of me and suddenly smile at some secret thought and then continue up the trail to where it bends back into the fog.

How does the author's specific word choice and stylistic devices affect the excerpt's tone? Be sure to use specific details from the text to support your answer.