Worst Possible Time.
The explosion knocked Andrei back but what sort of Semi-saint (though still at the early stage) would he be if he could not react fast enough to at least surround himself with Cosmic energy even if he could not run away from the explosion.
Even those not as strong as him, which was practically everyone in the room had shielded themselves despite also getting thrown away from the now-destroyed coffin to slam against the room's earthen and somewhat rocky wall.
*Bang!*
Ergo had used his Ax armament to charge Cosmic energy strong enough to create a shield wide enough to defend himself and prone Cirk on the ground but there was something about it that told Hal, who had now risen out of the rubble of rocks, that the half-naked brute had known of the explosive Array.
He was right.
Ergo was not as dumb as he looked and always had good instincts in battle. Pulling the Artifact out of the bony corpse's hand was such a situation where his instincts kicked in.