Indestructible Sword can be obtained by having Brynhildr reach Bond level 10.
Imperishable Flame is Brynhildr's Max Bond CE and exclusive to her.
Rashoumon event (Ibaraki Douji event)
Murder at the Kogetsukan
Inheritance of Glory
Ryougi Shiki (Saber)
Merlin
Jeanne d’Arc (Alter)
Altria Pendragon
Altera (Attila)
Altria Pendragon (Lancer)
Dragon Fang
Ereshkigal
Arthur Pendragon(Prototype)
Gorgon
Black Holy Grail (The Black Grail)