Before they face the last battle, Kurogane wants to settle a few things. (Since CLAMP have slacked off showing us the good stuff.)
"It’s practically a scratch, it heals right away, and it barely even hurts," Kurogane said flatly.
Fai blinked. "It… doesn’t?" His shoulders relaxed a shade.
"No, it doesn’t." Kurogane looked at Fai for a long, thoughtful moment before holding out his hand. "Come here. I’ll show you."