It is revealed to be a Grace, a blessing created by the Supreme Deity that was originally given to Mael of the Four Archangels. After Gowther used a forbidden spell to turn Mael into Estarossa, Sunshine then waited over 3,000 years until it found someone worthy - Escanor. After Mael allies with the Seven Deadly Sins, Escanor gives his Grace back to him so he could protect his friends.
Escanor's power is said to be unlike any other. He is at his weakest at midnight and his power peaks at noon. Starting from sunrise, his power begins to increase and he begins to grow larger and his personality changes from his submissive night-self to his prideful daytime-self, with the process reversing with the setting of the sun. In the daytime, his physical strength increases dramatically and he is able to radiate intense waves of light and heat easily capable of melting metal and vaporizing stone. Merlin hearkens his power to that of the actual Sun, the source of all life. Escanor is able to imbue Rhitta with his magic power, which causes the slashes from his axe to also burn his foes.
During noon Escanor's size grows considerably, becoming many times his own size. His magic power also vastly increases. When utilizing it he can create a miniature sun of pure magic power, whose heat is such that it can melt the armor of a Holy Knight several meters away just by being in its vicinity. It can also be controlled and directed for attacks, causing immense damage. When his power peaks at noon, the size of the ball increases accordingly, as does his strength.
At high noon, Escanor reaches the absolute peak of his power and he becomes The One, "the invincible incarnation of power", according to Merlin. This form only lasts for one minute. While in this form, Escanor's strength increases to the point where with a single strike of his hand, he could knock off Meliodas in his Assault Mode. His durability also grew to the point where he could easily shrug off Meliodas' Kami Chigiri without sustaining any damage. He was also able to eventually overcome Zeldris' Ominous Nebula attraction force, whereas previously he himself and Ludociel were powerless to resist it, his magic power leaving Chandler and Cusack shocked and Zeldris referring to Escanor as a monster for easily overcoming his magic power, and proceeded to break through the Demon Prince's magical ability with his Divine Sword Escanor before heavily wounding Zeldris with a simple finger jab.
However, as Sunshine is a power made for a Goddess Clan's member, Escanor cannot resist the effects of using that power on his human body, eventually damaging him to the point of coughing blood.
Sunshine let Mael's power increase as the sun goes up and decrease as the sun goes down. Ludociel, a powerful Archangel on his own, stated that his power could not keep up with Mael's power once noon was near.
As the Grace was made for an Archangel, Mael seems to have better control over it, as he radiates light and heat enough to melt metal, but without harming his allies. Unlike Escanor, Mael does not undergo any physical or personality changes. Also, Mael does not suffer any harm to his body.
Mael's power, even after high noon, is able to easily dispel the darkness surrounding Camelot. Mael also could defeat a very powerful being like the Original Demon with a single magic attack. Mael's prowess with Sunshine let him keep at bay Zeldris' Ominous Nebula, forcing the Demon to engage in physical combat.
- Cruel Sun「
無慈悲な太陽Kurūeru San; literally meaning "Merciless Sun"」: Escanor creates a miniature Sun, which radiates so much heat that it melts nearby armor. He can control it with hand gestures and strike his opponents with it, and it will increase in size as his power grows.
- Pride Flare「
炸裂する傲慢Puraido Furea; literally meaning "Exploding Arrogance"」: Escanor causes his Cruel Sun to flare with heat so intense it is capable of vaporizing a sizable lake in an instant.
- Pride Flare「
- Crazy Prominence「
爆発する矜持Kureijī Purominensu; literally meaning "Exploding Dignity"」: Escanor produces a large amount of miniature suns from his body that explode on impact.
- Greatest Sun「
偉大なる太陽Gureitesuto San」: Mael creates a miniature sun that can grows at will to a huge size, causing an immense explosion. 
- Helios Fair「
太陽の剛拳Heriosu Fea; literally meaning "Strong Fist of the Sun"」: After concentrating the power of the Sun from within his body into his fist, Mael performs a punch that shoot a torrent of fire. 
- The kanji used for "The One" (天上天下唯我独尊, Tenjō Tenge Yuiga Dokuson) are traditionally translated as "On heaven and earth, I alone am honored". These were the Buddha's first words when he was born. As a modern idiom these words are sometimes used to satirize self-aggrandizing conceit.
- This power is called by the Archangels Taiyou「
太 陽Taiyō」 (Sun in Japanese) instead of Sunshine「 太陽Sanshain」. The relevance behind this has yet to be revealed.