Energized Boomerangs contains canon Hero Factory information.
The Energized Boomerangs are standard-issue weapons used by Natalie Breez. They have the ability to be flung through the air or a vacuum by a Hero. It homes in on the nearest target with tracking sensors, and can cut with a molecule-thick blade edge. If a boomerang is lost, the blade immediately dulls and shuts off the built in circuitry, rendering it useless. The boomerangs are attached via her Harpoons.
In "Von Nebula" (Episode), Von Nebula created a black hole that sucked up the heroes' weapons, including hers. The weapons were presumed to be destroyed.