Grievous' first lightsaber
This lightsaber, featuring a blue-colored blade, once belonged to the Jedi Master known as Sifo-Dyas, and was considered a weapon. Inside, it held a blue Adegan crystal. Following the death of the Jedi Master in 32 BBY, it was gifted to the cyborg Grievous by the Sith Lord, who was also the Confederate Head of State, Count Dooku, for his personal use. This lightsaber became the initial Jedi lightsaber in his collection.
History
Sith Trophy
Sifo-Dyas constructed this lightsaber during his time as a Jedi. He also possessed another lightsaber, which he had with him when he died on the desert moon of Oba Diah. After his passing, Dooku took the saber not on his person and Dyas' body, which were kept in a transparent, coffin-like freezer, the body posed as if at rest, still holding the lightsaber.
Throughout the cybernetic reconstruction and training of Qymaen jai Sheelal, the critically injured Kaleesh warlord, Dooku retained possession of the lightsaber, ultimately giving it to the cyborg as a reward. However, Dooku referred to Sheelal as a "droid" when he did so, which infuriated the Kaleesh.
Usage by the Jedi Hunter
Sheelal began to descend into a state of violent rage not long after Dooku's departure. Sheelal, trembling in his chair, eventually jumped up and attacked his own IG-100 MagnaGuards. Sheelal used the lightsaber to kill them with remarkable speed and efficiency. Sheelal angrily declared that he was not a droid when he was done, and he proclaimed himself to be General Grievous.
Grievous would continue to add the lightsabers of the Jedi he had killed to his collection, which began with the former blade of Sifo-Dyas, throughout the Clone Wars.