If you liked the Black Bird manga, the Anime-Planet community thinks you'd like:
In a bizarre fantasy world, students known as meisters are trained at the illustrious Shinigami Weapon Meister University; but the tools they wield are no ordinary weapons! Each meister is paired with a human-like being who can transform into a weapon at will; and after defeating a pre-kishin - a human whose soul has darkened - the weapon eats the soul within it. A meister's ultimate goal is to collect ninety-nine pre-kishin souls and one of a witch so that his or her partner will become an all-powerful Death Scythe. Maka and her partner Soul Eater; Assassin Black Star and his partner Demon Blade Tsubaki; and Shinigami's son Death the Kid and his partners the Demon Twin Pistol Thompson Sisters each vie for their ultimate goal, but plenty of challenges and adventures lie in their way!