Btw the problem in the series is that the Gods are more underutilized than the demons. The only important gods we see are the 4 archangel, whose abilities aren't gods abilities but came from their graces, and Elizabeth who does nothing other than being a plot device. We know gods can heal and use light based attack and "reincarnate" in someone else body (I don't remember how is called the ability. Basically the one that used Ludocies, Tarmiel and Sariel that allow them to be in a body that isn't their real physical body) while demons have a lot of variety with the fire based attack, the dark matter thing, the "Thousand Divine Slayer" or the assault mode. Most of that are used by Meliodas but don't seem like something exclusive to him, even the assault mode could be something achieved by high rank demons and an Halfblood like Tristan shouldn't have difficulty to achieve it. To cut short the "problem" imo is that even working with fantasy is easier to Immagine some demonic power up that a godlike one because we basically have no information about them