Divine Mother's Mercy

Divine Mother's Mercy (聖母の慈悲) is an ability granted to Acqua of the Back, a former member of God's Right Seat, which he temporarily lost after the events in the Acqua of the Back Arc. Acqua regained it between English Civil War and World War III, but he completely lost it, along his nature as Saint, after absorbing half of Misha's Telesma.

Principles
This particular ability enables the user the remove any negative side-effects of any magic, including both costs and limitations (i.e. such as the user being able to use normal magic that even ordinary humans can, even if they were a member of God's Right Seat). Also, this limiter removal extends to the human body itself, enabling feats such as superhuman speed and strength. This phenomena is described as removal of any and all sin from the user, thus practically having it's user become a sinless human. Finally, the user can use this ability to gain immunity from punishment based attacks, as it can be used to expiate user's sins so that they won't be punished for them.

Weaknesses
As all other supernatural abilities, this ability has it's own restrictions. First, just being able to use this ability also means that one is and has the weaknesses of a member of God's Right Seat, said weaknesses also barring consistency with several of the weaknesses of a Saint, thus increasing the opponents chances to exploit the said weaknesses, especially should the user in question be both at the same time. As the majority of supernatural phenomena, Imagine Breaker can also overcome this ability. Lastly, removing one's physical limitations can potentially bring harm to one's own body during performing the said superhuman feats.

Acqua of the Back Arc
Acqua uses this ability in his battles against Kamijou Touma, Amakusa Church members and fellow (at that time) Saint Kanzaki Kaori, gaining great advantage and easily defeating most of his opponents, until his final battle in the same arc, after which he temporarily loses it in an explosion caused by the Amakusa Church's Saint Destroyer.

World War III Arc
After he regained it, Acqua uses the Divine Mother's Mercy to save Hamazura Shiage, Digurv and Glickin by the privateer helicopters and later to destroy the privateer's base. The ability is not shown anymore after he loses it in the attempt to incorporate Archangel Gabriel's incomplete form, Misha Kreutzev.

Trivia

 * The superhuman feats performed by God's Right Seat member Acqua of the Back with this ability earned him the nickname 'Superman' in the fan base.