Lex naturally could not catch the orange orb at the speed of light. Yet his intuition could predict its trajectory and path even before it launched, giving Lex plenty of time to prepare.
Although the orb was quite a bit larger than his hand, on a whim he felt like testing out Impervious hands.
Using the technique cost a lot of spirit energy, but Lex was not in his flow state, where he always did the most efficient action. In normal life, it was okay to be wasteful sometimes.
The technique's appearance was very lackluster, in that nothing special appeared on his hands. It was as if a technique wasn't being used at all.
Just as he held out his hand in place, the aliens launched the attack. While the orange orb had no trouble breaking through the Imperial shield, the moment it touched Lex's hand, it lost all of its momentum.