Technological achievement
Shinzo creates his own doppleganger and binds it to a weapon.
After making and wielding Nalu, Shinzo sets out to make a more permanent spirit weapon for him to use. After watching the Knight's Ceremony where they fight a doppleganger, Shinzo summons his own doppleganger by himself. He discovers that dopplegangers have perfect autonomy if made by oneself rather than by a group of others. He makes a pact with his doppleganger to bathe the world in blood, and he binds him to a staff.