There are two, among those organizations known universally in the Empire, that traditionally wear full-face-hiding masks.
The first of these is the Masked Order of the Unnamed, eikone of seals, secrets, and mysteries. The intrigants who serve the Unnamed wear masks of the same serene, beautiful face, anonymous within their night-purple robes. The masks do differ in materials: masks of polished silver, of pale ivory, of rose porcelain, blue wood, or midnight onyx. These have meaning – the Unnamed permits nothing less – but centuries of studies by scholars outside the Order have not revealed it. (And besides, if they did, the Unnamed’s Inner Circle would imbue them with a further esoteric meaning, if they do not already possess one or more.)
The second is the Eupraxic Order of Reason, who wear masks of smoky glass beneath hooded robes of gray, upon closer inspection a twisting fractal pattern of black and white intertwined in deep complexity, but never blended. As is their practice, they declare their meaning openly: they go masked and cloaked that those who seek their counsel will see nothing, perceive nothing, consider nothing but the argument itself, and that no personal characteristic of theirs may be permitted to taint this in the eyes of their clients.
Intimidation, however, is evidently not considered a problem by either group.