Going with the change on abilities Artemis mentioned for bounts/hollows/superhumans, I am just posting my second and third abilities for the staff's review.
Second ability: Sirenenlied (Siren Song) - An ability that makes use of Sirene's spirit power mixed with her voice. By singing, her voice travels into the opponent's brain through their ears and puts them into a temporary trance that messes with their perception and their reflexes. (It's like giving them an instant drunken state) The state can be extended if Sirene continuously sings, but she is unable to use other abilities simultaneously. The range of effectiveness of this ability is greatly reduced if she uses it in her sword core form, since she has no physical mouth in that state.
Third ability: Schlachtruf (War Cry) - The exact opposite of Sirenenlied, Schlachtruf uses Sirene's power and voice to effect Akira's brain in a positive way. Her voice triggers a reaction in his brain that lifts the natural limiters on his muscles, increasing his strength, speed, and reflexes. Overuse of this ability can cause damage in Akira's body that he needs to recover from (A liberty not always available if in the middle of a fight). Usable in core form, but the effect doesn't last as long.