You've seen it with your own eyes.

Optimus Prime, grabbing the hilt of his sword sticking out of a piece of rock, was able to pull out an ancient artifact, which glowed blue under the influence of his hand.

Even after falling from the height to which the Decipticons had lifted this piece of rock, he landed without much difficulty, and the sword still sparkled in his hands. It was the Star Saber.

Optimus was still examining the sword, as if he hadn't noticed that a huge stone was rolling right at him. The team started to worry, trying to tell him to move away, but he just turned around and cut the rock in two with one movement. All the power that was in the sword was awakened under the Prime's hand.