A Conceptual Weapon stored in the Reality Marble Unlimited Blade Works used by Archer and Emiya Shirou in Fate/Stay Night's Unlimited Blade Works and Heaven's Feel routes. Presented as a purple/pink energy shield composed of seven concentric circular/flower-petal-shaped layers arranged from smallest to largest, with the largest facing the user.
Each layer is as strong as a fortress wall, and the shield as a whole carries the "concept" of "blocking any projectile attack." The Conceptual Weapon is based on Telamonian Ajax's (Ajax the Greater's) shield, which consisted of seven cowhides over a layer of bronze; during the Trojan War (according to the Iliad), the shield blocked all attacks aimed at Ajax and his comrade Teucer without taking damage until it blocked Hector's spear, which pierced the first six layers before being stopped by the seventh. In the Unlimited Blade Works route, Lancer uses Gae Bolg's thrown attack to the same effect in his second battle against Archer. During Shirou's battle against Gilgamesh, Archer used Rho Aias to protect the former, and in the anime adaptation Shirou is shown using the shield during the battle. Also, in the Heaven's Feel route, Shirou used the shield against Saber Alter's Excalibur Morgan in order to protect Rider.