All of FFVI's characters had something about them they had to realize before the end of the game. So I'd say the theme wouldn't really be 'war' more so 'Fighting inner demons' or something to that extent. In the world of ruin you can't even get everyone back unless they fight their inner demons and before that they obviously have problems they need to overcome, more so in this game than any other.

Or maybe FFVI can be 'Finding inner self.'