He has learned Gankutsuou's weakness. It replaces the body of its host with crystalline structure. If there's any man left inside the Count, the heart will be the weak point, and Franz has a conventional sword inside the armor to strike when the Count is close enough.
Sadly, the Count's heart has already been transformed.
Albert wakes up and realizes what has happened. He races to the duel site, but is too late to stop it.
Franz dies in his arms.