Final Aeon/Sin fights

Woe to the conquorer - the victor of a fight is sad because he/she has won->summoner dies, final aeon becomes sin
An act of contrition - fought to repent for a sin he/she has committed->final aeon kills sins, then becomes him.
The only suitable music - the only suitable music
Would be a lacrimosa - as i understand it this is a sad piece of music, and the final work of mozart committed to paper