The Blades of Time were the artifact of Vector Prime. Not a weapon, per se, the Blades were represented more as a mandala or hourglass, through which Vector Prime focused his space-time powers.
Solus Prime was in the process of creating a new mandala for Vector Prime when she was killed, although whether it would have been similarly powerful is unknown.
When the once idealistic Vector Prime despaired after the War of the Primes and sealed himself away in a peculiar pocket dimension, he left the Blades of Time in the hands of his comrade Nexus Prime. When assembled correctly, these five pieces of metal are capable of opening a portal to Vector Prime's secret sanctuary.
However, when Nexus Prime split himself into five parts in order to protect the Star Saber, the Blades were also divvied up, and his five amnesiac components soon lost track of them.