Blightwing
Blightwing was a monster, presumably a powerful winged creature, defeated by a wielder of Heartseeker.
“"You're right," said the sword. "You're right that I am an instrument of Melkar. I am the legendary blade Heartseeker, wielded by the most famous half-bloods in orcish history! When the Formian King invaded Gazluk, Amatuk used me to kill him. I am the blade that slew Blightwing! Your mother used me to kill the Frost Siren. Half-bloods don't trust easily, but your mother trusted me. You need to trust me!"