Comments posted to our Dark Souls 3 Wiki
it's like a reverse cosmic egg, instead of producing anything associated with life or constructive growth it manifests death and mass destruction
Probably someone already pointed this but the curtains and veils surrounding her form a bonfire, as you can see in the concept art. Symbolically, she's keeping the bonfire lit. This is probably related to her role in the deceive of the undead humans.
She is a very interesting character indeed but what is more interesting is the item she is holding, the shell in my theory it was protecting or more likely imprisoning the dark soul of man within itself but for some reason it was broken , im not going to try and explain why is it broken but rather what it is, in Dark Souls 3 there is a spell that as you can remember was in DS 1 and that sorcery is "Repair" well yes it's in the game and whats with it you may ask. Have you read the description? If not then let me show you what piqued my interest: "While the effects of this spell are rather subtle, its foundations are a well-guarded secret. Light is time, and the reversal of its effects is a forbidden art." - "Light is time" This thing in hands of Filianore, cracked but not completely, when touched breaks and glows brightly before sending us forward in time. So whatever it truly was im unsure but what im sure of is that tremendous amount of light was involved in its creation...
Cut your damn toenails Filianore