Kanesada Kuji

"“Wanna see? It’s a blade the likes of which you’ll rarely see these days,” she says as she begins to extract the blade completely from the bag, but Miss Tōko stops her.

“Shiki, I know that’s an old piece of history. Don’t even think of pulling that out unless you want to cut down the ward around this place.” Shiki freezes as soon as she says that. “It’s impressive and all, and I can even read the Kuji: ‘let the warrior-god light my way.’ It’s cool. But the wards that I’ve put up won’t be a match for a sword with that kind of history.”

With Miss Tōko’s words that seemed like they were warning of some great tragedy if we disobey her, Shiki has little choice except to put the blade away again."

- Volume 2, Paradox Spiral, Page 109

"Will it be possible to repair the antique katana now that it’s broken? <Yasunosuke>

Nasu: Even if it was reforged, the years it had accumulated before would be lost.
Takeuchi: A lot of people asked this question. Since I thought it was going to be Shiki’s final weapon, too, I was pretty shocked when it broke almost as soon as it finally appeared!
Nasu: That’s how ultimate weapons should be."

Kara no Kyoukai - Chapter 5: “Paradox Spiral” Movies Q & A Pamphlets