She was originally planned to coincide with SoA... but that was ditched at some point and her plot was shifted to Rhapsodies.
So it's not too surprising that we'll get her (or that her potential BPs were cannibalized for the RoV fight and Teles).
Though I AM surprised that they'd go back and fill her out.
They didn't even really do that for Cait Sith. (She got no BPs 76~98!)
Hysteric Assault - Fivefold attack that deals Physical Damage to the target. Also drains HP proportional to the damage it dealt.
Lunatic Voice - Conal target Mute (unremovable silence).
Sonic Buffet - Conal target Element: Wind magic damage. Additional Effect: 2~3 Dispel.
Entice - Conal target Charm. Only used during the duration of Soul Voice.
Clarsach Call (used at 25%) - High Element: Wind magic damage with a radius exceeding 25-30 yalms. Additional Effect: Magic Attack, Magic Accuracy, Magic Evasion, Magic Defense Bonuses applied to Siren.
Add in AeroII and AeroIV... that makes 7 BPs. Almost a full set.
Also: calling it forever ago, her Favor is Acc+.