This angel sings a song of praise. This may surprise us because we invariably lament a development as catastrophic as all water becoming blood (and any official in our day responsible for water management would be fired if such a calamity happened under his watch). Children of God on earth want to know why this angel rejoices and will want to take their cue from him.
5 Et j'entendis l'ange des eaux qui disait: Tu es juste, toi qui es, et qui étais; tu es saint, parce que tu as exercé ce jugement.