I had this thought, what if it turns out that the Dazzlings have a master, the actual Horseman of War. Who took them in and adopted them after they were banished and as the Daughters of War, he gave them their pendants so that they could serve him by bringing conflict wherever they went like they used to back in Equestria.

When He broke the second seal, I heard the second living creature saying, “Come.” And another, a red horse, went out; and to him who sat on it, it was granted to take peace from the earth, and that men would slay one another; and a great sword was given to him.
— Revelation 6:3-4˄ NASB

Other that the singing and not as intense, probably from lack of power, Dazzlings's powers do sound similar.

3713893 I have a theory that The Dazzlings aren't the only ones of their kind. I personally think that they were raised as black sheep whilst the others were trained as war-making champions of song. They only truly tried their luck at Equestria when their clan was hunted to near-extinction, and now they are the last of their kind. Except, they're not. They have rivals. Three male sirens with the EXACT same powers as them, long ago, the Dazzlings duelled the Roaring Voices (you think of a better group name) a group of males who were to receive a special siren knighthood, but had to face a foe to prove themselves. They chose Adagio, Aria and Sonata, mainly because they wanted to face someone on their level of power. The fight was inconclusive at the time, since a hunt happened in the middle of it, which called the fight off in the middle of it. Fortissimo, Allegro and Orchestral were thought long dead after that, but The Dazzlings got one final look at me before being forced into the human world, along with their powers. Fortissimo looked at Adagio with a scornful look, and merely turned and flew away with Allegro and Orchestral, before Starswirl even knew they too were sirens. And before they were sent away, Adagio shed a tear as she saw Fortissimo, Allegro and Orchestral flying off into the distance.

That's my theory, what about yours?

3714007 I actually don't have any theories about the Dazzlings before their banishment but based on what I've read in the MLP comics I think the Dazzlings are Kelpies (although their appearances hasn't been consistent). So your not far off in believing that they are not the only ones of their kind.

If you read the flashback scene in Chapter Three of this story, it sums up my theory. But, I'll admit my theory serves a pretty big plot arc.

Astral Sketch, we're thinking along similar lines here... Hmmm...