The Grace represents the interconnection of everything, the world of life and the world of the dead, Additive and Subtractive, as well as the spark of the gift that runs though it all. The Grace does more though, than simply represent Additive and Subtractive magic, Creation and obliteration, life and death, it connects them into a cohesive whole. The power of Orden deals with life, death and the whole nature of existence so the key also needs to have both sides. It needs both Additive and Subtractive, life and death to be complete.