Powers:
Pre-curse: super strength, super speed, invulnerability, plus an all-element Sun Metal ring that could transform objects, allow him to fly safely at multi-light speed and travel through time and space. These powers came from his exposure to Sunergy, energy generated by Sun Metal, a metal formed by fusing all of the elements together into a radioactive compound, created by his genius father. Self-duplication; he created an identical version of himself so one Atom could roam the solar system having adventures while the other could remain at home and live the normal life of a super powered teenager.
Currently: now a powerful, though immature wizard who has demonstrated the abilities to fly, enclose himself in a protective shield, materialize simple objects (such as a puddle of oil), teleport others, sense magic, clairvoyance and clairaudience through the casting of illusions.

Source of Powers: Formerly, Atom was exposed to Sunergy while growing up. He later discovered a wishing ring made of Sun Metal that gave him additional powers. When he was cursed by Blaze and Satanus (see below) his superhuman powers were stripped away, and he gained magical abilities instead.

Knowledge and skills: Atom is a genius. He has firsthand knowledge of several of the planets in the solar system and also Mercury in the far future. He is a very good baseball player. And he is a grad student in Magical Studies at Grimoire Academy.
Weapons and Gadgets: his Sunmetal ring; as a mage, his magical apparatus and tomes

History:
Atom was born in 1925 and his exposure to Sunergy while growing up had caused him to develop amazing super-powers. During his youth, he had been nicknamed the Boy Wizard because of the amazing super-strength, speed, and invulnerability that had been granted to him by his father, brilliant physicist Stuart Blake. Atom also been left an amazing Sunergy ring by his father that could make the impossible become true.

In 1950, he had battled and lost to the demons Blaze and Satanus, who had punished him by reverting him to perpetual six-year-old boyhood and stipping away his super powers, though they had accidentally granted him magical powers instead. In addition, his altered body chemistry forced him to sleep for hours to recharge after using his magical powers. This enforced nap proved rather rather inconvenient in the middle of several battles versus magical foes. During his nearly forty years stuck with the body and emotional maturity of a young child, his control of his magic grew, and Atom repeatedly attempted and failed) to cure his condition — there might be many people who thought immortality to be a blessing, but Atom realized that being stuck at six forever would be intolerable. He had been twenty-five and courting the woman he planned to marry when the demons had cursed him, and he remembered the glimpses he’d had of some of the joys of life that he would forever be denied if he remained trapped at six. Eventually he had enrolled at the Grimoire Academy, in the hopes of learning enough magic to lift the curse.

Atom has already reaped unexpected benefits from his studies, a way to alleviate his magical narcolepsy. In an advanced alchemy class, he’d learned to create an energy potion — something like Jolt Cola, only magically much more effective. As long as he could drink a shot of his potion every couple of hours, he could keep his affliction under control.

(Partial) list of 5EP appearances: (links)
Atom Blake the Boy Wizard, Wow Comics #1 (Winter, 1940-1941)
The Castaways
Magic and Demons and Ghouls, Oh My!