The mage isn't probably the concubine's lover. The part where he said "there is no longer someone who can kill the devil", probably indicates that the concubine's lover is dead. There is also where the kid said, "I thought I wouldn't see that fire again" which also adds to the possibility that he is really dead. The concubine's lover has both silver hair and eyes while the evil mage has blue hair. My theory is that the concubine's lover must have been a powerful mage who tried to defeat the evil mage but died along the way
SPOILER WARNING
The mage isn't probably the concubine's lover. The part where he said "there is no longer someone who can kill the devil", probably indicates that the concubine's lover is dead. There is also where the kid said, "I thought I wouldn't see that fire again" which also adds to the possibility that he is really dead. The concubine's lover has both silver hair and eyes while the evil mage has blue hair. My theory is that the concubine's lover must have been a powerful mage who tried to defeat the evil mage but died along the way