Power *Spoilers*
Hiro can change origin energy into any energy, be it Holy, Demonic, Mana, Touki, Senjustsu or Sorcery. Still the most useful among them is Devil magic which lets him cast spells with imagination.
His physique is Origin Body which lets him absorb the energy in the atmosphere and simultaneously convert it into origin energy.
He can forge any crest and signature of magic or demonic power with his origin energy.
As a rare half devil, he wasn't born with wings. He can still fly with wings made out of Origin energy.
He can copy the aura of his surroundings to hide his own aura. It requires him to concentrate on the surroundings so it's hard to keep this up in a battle.
He can use abilities out of 72 Devil Clans, only abilities that requires the manipulation of one's energy or aura. He need to work hard on to master them and improve efficiency.
In theory, he can even copy the unique abilities possessed by Sacred gears. The current abilities he is learning are -
«Power of Destruction» from Bael Clan
«Worthlessness» from Belial Clan
«Regeneration» from Phenex Clan
«Lion Tamer» from Vapula Clan
«Dragon Tamer» from Buné Clan
«Water Manipulation» from Sitri Clan
«Horse Tamer» from Furcus Clan
«Crack» from Belphegor Clan
«Time Manipulation» from Agares Clan
«Charm» from Balam Clan
«Bear Tamer» from Purson Clan
«Wind Manipulation» fromViné Clan
«Demonic perception» from Beleth Clan
«Steal» from Velfar Clan
«Demonic lightning» from Furtur Clan
«Flash» from Shaz Clan
«Flame manipulation» from Aamon Clan
«Stealth» from Goap Clan
«Aura Perception» from Vasago Clan
«Healing» from Vaper Clan
In future his abilities will evolve as he himself evolves.