I agree -- this one nameless solider nicely captures them all. Her story is a wonderfully meaty look at what FTT battles are like without the glossing-over that HP and MP provide, and I already feel bad when I dismiss anything (especially chocobos! Aaiiieee!), but I'll feel particularly bad now.
The fact that she had a sexual relationship had me nervous for a while, since that could easily take a turn for the cliched, but it's nice to see that you kept it anticlimactic and...not insignificant, exactly, but as a tiny facet of their relationship and of Nameless Soldier's being. The romantic feelings don't choke out everything else, which seems all too rare in fiction.
In short, excellent job fleshing out the most generic of characters, and making the reader feel for her.