I am unique among my kind, though I do not look it at first glance. I make beautiful music as well, if not better, than my kin. But I was created with magic.
I was once something wonderful, a gift to my creator's beloved little sister. I was adored, and my music appreciated. The girl and I were a team. With help, I could even be magical.
I am still that way, but my partner has been corrupted. She used me to kill, to cause others weaker than she to suffer.
I have a power that is useful, but she doesn't know. It could create happiness again, but my partner doesn't want to bring joy anymore. She only uses me for sad songs as she wallows in self-pity and a thirst for vengeance.
I am a sad musical instrument, but I won't tell you which one. I have inherited my partner's naturally secretive nature.