Corona Glaive

The Corona Glaive is a powerful sword stored in the archives of Iacon. Possessing the ability to combine with a wielder's blaster, the Glaive is typically carried by Autobot heroes.

Transformers: Fall of Cybertron
Aboard the Ark, during the Autobots' last desperate battle to evacuate their home planet of Cybertron, Optimus Prime (wielding what appeared to be the Corona Glaive) faced off against a similarly sword-wielding Megatron.