Irish for "blessing to ye," used as "goodbye." This exchange establishes a connection between Miss Ivors and Gretta that points to questions about the relationship between Gretta and Gabriel. If we think of Miss Ivors as having been one of the few "live" persons at a generally dead party, then perhaps this liveliness is now passed (perhaps ambiguously) to Gretta, in the form of an Irish blessing said with a laugh and a cry.
'in a kink of high-pitched bronchitic laughter' 哈哈哈哈哈哈哈
THE COCTEAU TWINS, PHOTO SESSION. CIRCA 1990'S BY PAUL COX.