A razor-ring is a concealed weapon in the form of a ring with a razor-sharp blade which can be concealed in the closed hand but which can cause severe damage if used to e.g. slap. Kallystine possesses one, with which she hits Jame, cutting her cheek down to the bone and tearing it wide open. She does this as revenge for the damage to her face caused when she's pushed headfirst into the basin containing an aging liquid; she's convinced that Jame must have been the one at fault, although it seems much more likely that Kallystine's half-breed maid-servant did it; Kallystine had ruined the girl's hand with the liquid, experimenting with it, and cut off the girl's braid to use as a fall before giving it back, saying she didn't want it anymore. The maid hangs herself with the braid shortly after, reinforcing the likelihood that it was her.
Kallystine later tries to slap Torisen with the razor-ring, but is thwarted by Lyra grabbing her other hand and pulling her off balance; Lyra excuses this as an accident. The attack gives Torisen a valid reason to break her contract as his limited-term consort, to his ill-concealed satisfaction.