Many of us have been watching closely for anything Sister's related. Games Workshop has started the Battle Sister Bulletin, starting off with the iconography.
via the Warhammer Community
https://www.warhammer-community.com/2019/02/18/18th-feb-battle-sister-bulletin-part-1-adepta-sororitas-iconographygw-homepage-post-1/
Welcome to your very first Battle Sister Bulletin! As promised in the Las Vegas Open Warhammer Preview, we’re going to be keeping you up to date throughout the entire process with all the latest developments as the new miniatures range takes shape. In our inaugural bulletin, we’ll be taking a look at some of the concept art that has helped to define the iconography across the new range.
One of the most integral features of Warhammer 40,000 is the iconography that helps define each faction (apart from the Tyranids – though we’re sure that the Hive Mind probably experimented with bio-banners at some point…). From the symbolic allegiance denoted by the Imperial Aquila to icons such as the blood drop of the Blood Angels or the skull rune of Khorne’s followers, such imagery is an intrinsic part of Warhammer 40,000. When it came to redesigning the Adepta Sororitas range, the iconography was, therefore, one of the first aspects that the design team looked at.
Here is a selection of some of the earliest concept sketches, and they feature an interesting juxtaposition within them. Many contrast softer themes such as wings, angels and flowers with stronger, more aggressive ones – the roses are complemented by thorny briars and clenched fists, while the ornate chalices are accompanied by skulls, swords and flames. The iconic fleur-de-lys – the unifying symbol used by the Adepta Sororitasand the non-militant orders that support them – also regularly appears throughout.
Of course, each Order of the Adepta Sororitas has its own iconographical nuances too. As the spiritual inheritors of the Daughters of the Emperor, the Order of the Ebon Chalice, for example, take much of the inspiration for their iconography from their part in the execution of the traitorous High Lord Goge Vandire. Images such as severed heads and relic blades are clear references to the violent, but storied, origins of the Order.
Once the Adepta Sororitas iconography has been conceptualised, it can help to influence some of the details on the miniatures themselves. These themes may eventually feature on their armour, banners, wargear and transfer sheets, or even in their artwork, though the purpose of concept art is to inspire rather than dictate.