A weapon is, in the end, just a weapon.
After losing one's free will, an Extraordinary Creation becomes both a source of power and a cage.
Atlas might be powerful, having once defeated a Domain Level Powerhouse, but his body and will were ultimately just a vessel for the Extraordinary Creation.
Relying on this alone was far from enough to fight Reinhardt.
...
WHOOSH—!
The sound of rending air, wrapped in a sonic boom, tore through the rain.
Propelled by high-temperature jets, Atlas's figure left behind an afterimage. The whistling hammer grazed Reinhardt's Power Armor, sending sparks flying as it smashed heavily into the ground.
BANG—!
The already old ground instantly shattered, and spiderweb cracks spread in all directions.
Puddles collected in the crevices between the stone bricks exploded into a spray of water, rising and falling with a SPLASH.
