BlackBird

The BlackBird is the weapon wielded by Vesper.

Its core is a circle that grows of a metal piece attached to a wristband. The circle generates blades, which come out attached to it. These blades (with the symbol of the Necromancer on them) can be used as to make it a sword, or can be shot off, causing an explosion at their impact. The blade can also be split partway through the Necromancer Symbol, with a string connecting the parts. The core is also sharp by itself, and generates power, allowing elemental abilities to be embedded into the blades, with the elemental abilities and the color scheme being affected by which Pearl is inside it. As shown near the end of Episode 5, the BlackBird cannot be used too much in a short time, or it will temporarily run out of power.