Who is Grand Honored Matre Logno from Chapterhouse: Dune and what is their importance?

Grand Honored Matre Logno is a Grand Dame and senior aide to the Great Honored Matre, Logno is first seen quaking at the darkness in which the Grand Honored Matre sleeps (and reportedly beds Futars). Logno carefully stays four paces behind Dama, lest she be killed, until Reverend Mother Superior Darwi Odrade comes to Junction, ostensibly to surrender to the Honored Matres. Odrade finds the blonde-haired, fierce-eyed Longo more impressive than plain Dama. Odrade is puzzled to see Logno watching Dama drink wine after being lambasted for failing to poison Odrade.