For starters we're having our doubts that you thoroughly read through the OP. But we're giving you the benefit of the doubt and glazing over that.

Your CS has been denied for three specific reasons:

1: We already have two "knight" like characters. Please use more variety. We were thinking maybe go the route of a spellsword or a devoted champion of the old gods.
2: Magic requires deep concentration, most knights would NOT be able to focus enough in the middle of battle to pull off anything useful. Magic is young in this world and even highly trained magic specialists struggle with it. We would need a good reason for your character to be using it. Gotta be practical yo.
3: There are no "Demons" in Aeon. The Outlander brought magic, not demons. This sort of magic is mostly what you would call elemental or psychokinetic or what have you. There is blood magic in the history of Aeon in the form of primitive rituals in a sort of witchcraft or voodoo style. Its results are often dubious.

For future clarification, there is no "spirit world." in this RP. There are no actual Demonic or Angelica or spiritual incarnations.  This isn't to say your character cannot follow ancient Gods or traditions as residents of this world can and will believe in such. There are tales of such in the History of Aeon, but it does not literally exist. That tome he carries, for example, would be totally fine but most would consider it to be more along the lines of a grimoire or a an Enochian bible. Possibly dangerous. Mostly just cool and occult.