Wow, this is really painful. In a good way! The only part that made me blink was the end. I'm not sure that I could see Yuna taking his life with her own hands like that, even if he was going to die. Lulu I could see doing that, though I have to stretch to see Yuna doing it. Maybe in light of how she learned to fight in FFX-2, I could see it, but Yuna from FFX was just...a lot gentler and a lot more scared in some ways, in my mind, at least. :shrugs: I don't think that it ruins the characterization at all, just that I found it different from how I viewed her.
Your ambiance and the visceral details of the soldier's wounds sets up a very raw and powerful picture. Great job. :)