Sariels are Aragami best known for their resemblance to a human woman fused with a butterfly, along with their seductive ways, blue-ish colors, and wide variety of poisonous and long-range energy blasts.
This one has evolved a little further, enough to warrant her own classification among those at Fenrir as a Type 1 Deusphage, along with a small selection of classified photos from those lucky enough to encounter her and survive to escape.
What is known about her is that the human part of her is more... developed than normal Sariels, enough that the few men that have seen her have talked at great length about the supposed firmness and size of her heaving bosom. Some reports also mention how the view underneath her skirt is quite feminine, while other reports state the exact opposite. The pollen she spreads from under her skirt heightens sensitivity and suggestibility, and a high enough dosage will make almost anyone putty in her hands for at least fifteen minutes. The milk she produces from her ample breasts is also laced with this pollen.
It appears to be intelligent enough, as according to reports, it has been shown to talk to humans it encounters. Little else is known, and an outstanding mission for her defeat has yet to be cleared. No weaknesses have been verified. It has been postulated that feeding on God Eaters and God Arcs may have been the cause for her evolution, thus only high-ranking God Eaters are authorized to undertake this mission.
For more details, God Eaters may check in at Fenrir to read more. Additional details about Tessiel may be found here.
As an Aragami, Tessiel is practically invincible to almost everything, be it guns, swords, or nuclear explosions. The only things capable of inflicting any massive damage to her are God Arcs or other Aragami, unless she's actually willing to lower her defenses.
Tessiel has a slight weakness to cold (mainly cold-element God Arcs), but nothing huge like many other Aragami.
Even if Tessiel does die somehow, either by God Eaters managing to best her or whatever, Tessiel, like all Aragami, is made out of Oracle Cells. If she does die, it's a relatively simple matter for her to reform later on.
Also, since she's made out of Oracle Cells, it's easy for her to change her body almost at will, by redistributing her cells where ever she'd like, or taking in/releasing Oracle Cells out of/into the surroundings. Her cock, for example, isn't always present, but she can make it appear at will.
She has a major sweet tooth, mainly because humans and other things she eats don't often taste sweet.
Her pollen can be scattered from underneath her skirt, and her milk and other fluids are laced with it as well, enhancing sensitivity and suggestibility in whoever breathes/tastes it. The more you take in, the bigger the effect.
Tessiel has an ass (and what an ass), but no anus. Anything she digests ends up fully converted and used to fuel her body.
While she prefers to take prey in through unbirthing or her cock, she's not averse to just gulping someone down, or even hugging them and simply pulling their body into hers.
Apparently Tessiel is quite virile, having impregnated Liliata after a fun bout of lovemaking...or two, or three...