The mind of a wizard is more open to the more esoteric elements of his surroundings - this is why he is able to perceive the weave of the Great Tapestry that is the multiverse, and pull at the strings. This increased sensitivity can manifest in several ways.
Victorian Ladies used to use their decorative fans to communicate simple messages to their lovers while chaperones or husbands watched. These messages include "Yes", "No", "We've been discovered", "When can I meet you", etc. An Assassin's League of women could easily use this secret language to their advantage, sending messages to each other in hopes of reaching their target at a crowded ball.