Conceptual Armament

① When the body of a vampire is destroyed, the Curse of Restoration will return it to normal in a short period of time. In order to truly and completely destroy a vampire, an external factor is needed to neutralize the Curse of Restoration faster than the curse can restore the body. Mystic items and such that are capable of doing so are called conceptual weapons.
② A final trump card or secret ability used to dispose of members of the blood-sucking species who were never human at any point in time.

Colorful MOON Tsukihime: Tsukihime Glossary
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A weapon created to go beyond mere physical interference, and exert influence on concepts, natural providence, and space.
For instance, something that nullifies ”eternal youth“ by overwriting it with the idea of ”natural lifespan.“
Ciel's Seventh Holy Scripture contains the dual concepts of “reincarnation criticism” and “eternity without permanence.”
By the way, after being killed by Shiki, Arcueid had at first mistakenly assumed that he must possess some kind of powerful conceptual armament.

MB Act Cadenza PS2 Manual: Tsukihime Dictionary