Here are the thing you should remember in this Tensura Alternate Universe {I might add more as the story develop}
[world]
The balance between the angels, demon, and spirits are going to be the demon is strong against spirits, the spirits are strong against angels, the angels are strong against demons
Primordial demons are going to as strong as a low true demon lord and even defeat it if the said demon lord doesn't have a broken skills
[magic]
I made the magic a little more complex as every element are tied to concepts, for example example the water element magic is tied to concepts like purify, cleaning, changeable, flow etc.
but the farther the concept relates to the element the weaker it is. Another example would be fire has the concept of [life] and some crazy mages {pyromaniac} use fire to heal themselves while feeling the fire burning on their skin while healing minimally. On the other hand wood magic also has the concept of [life] but its effect is countless time better than the fire, as with strong enough mage there is no problem to regrow an entire limbs.