1) Who can he turn into exactly? Is it anyone who fills the role of a warrior? Is it just people from human history or are other species included like aliens? How far back into history can he go to retrieve a spirit, can he just pull the spirit of a soldier that died recently giving him modern weaponry?
2) What exactly are his limitations when he is channeling a spirit? Is he still vulnerable to normal stuff like stabbing, bashing, bullet wounds? Is he only as physically capable as the person he is channeling?
3) What type of magic can he use when he is channeling a spirit that has access to it, like Arthur.
4) Why would he come to a school to train him to use his power when his power is literally to instantly know all the skills of former warriors.
5) What do you mean by Caliburn? I thought Caliburn is Excalibur, they are just different names for the same weapon. Anywho what can Caliburn/Excalibur do exactly, there are many different forms of the sword with many different descriptions of its power.