Angel-bloods are the children of Angels. Sometimes they are called Nephilim.
Angel-bloods first came about when men increased in numbers on earth and daughters were born to them. The sons of God (full-blooded angels) saw that they were beautiful and married them. Their offspring were Dimidius. These first angel-bloods then became fruitful with either another angel-blood, full-blood angel or human. This chain reaction introduced many other angel-bloods, Quartarius, Triplare and the many other possibilities for an angel-blood in between.
Angel-bloods have always possessed beauty, skills in all areas (stretching from physical activities to school subjects), the ability to summon wings and fly, the ability to call glory which can be used for a wide variety of purposes depending on their 'rank' (Triplare, Dimidius, Quartarius) and abilities depending on their rank.