Okay, Since I don't want to reveal what Deus has been doing during the Timeskip I'll keep it short. Deus has been immersed in the study of Alchemy. Therefore he has also been studying about the Philosopher's Stone. He has been looking for a way to create it. So far all he has been able to build is Fake Philosopher Stones which break after Continuous use, That is why he is able to use Electricy Manipulation for now. Deus is doing this sparring match as a way to see how long it takes for the Stone to overload. After the battle the Stone will break, and the only thinf that Deus can do afterwards is Transmute metals into weapons.
EDIT: If you want I can just scratch all that and just put Electricity Manipulation under Ability Creation insted of Alchemy,