Arceau's Lucky Coin Divine Artifact
When Arceau's full-powered attack collided with Keith's fist construct, the power of Keith's fist construct was weakening at a fast rate. Of course, Arceau's power was weakening alongside Keith's fist construct.
But, compared to the rate of Keith's fist construct being weakened, Arceau expended more energy and it didn't take that long for her to expend all of the mana and divinity that she had recovered from sacrificing the powerhouses in her world.
There was only 30% energy left in Arceau's energy reserves but Keith's fist construct still had 40% energy left. Even if Arceau expended all of her energy, it wouldn't be as easy as 40% subtracted by 30% since Keith's fist construct possessed higher quality in both mana and divinity.
From her estimation, even if she sacrificed all 30% of her energy, only 10% of Keith's fist construct would be reduced. So even if she expended all of her energy, Keith's fist construct would still have 30% remaining power.