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 And I heard the angel in charge of the waters say, “Just are you, O Holy One, who is and who was, for you brought these judgments.