White skin, haunting songs, and commanding undead. While I don't know how much of a scholar Talogan may be, putting together some information from Nyx and tales you would've heard from various sailors and pirates trying to pass the time, you could conclude that the creature controlling these undead is some sort of spirit, a ghost, and most likely: A Banshee. Women who have died horrifically, their rage and hatred turning them into an undead creature far more threatening than a mere zombie or skeleton. And compared to the relative mindlessness of the drowned, a Banshee is a fully sentient undead, albeit one who feels perpetual torment and hatred for the living.