There's 107 rings for the trophy
Also, do you need to max the covenants on a single character?
You don't have to max all the covenants, only the ones that give rings or spells. AFAIK you need to have all the relevant items/spells for a trophy on one character though, yes.
Also the Aldritch Faithful covenant description uses even more specific language about the coming age:
The holy symbol of the Cathedral of the Deep, and crest of those who see beyond fire to the age of deep waters. Equip to pledge onself to the Aldrich Faithful covenant.
Deep sea, deep waters. No abyss. So that's probably the Cathedral's namesake.
Also I found the name of one of Yuria's sisters: Liliane. From the description of Dark Blade: "The third daughter Liliane, one of the founders of the Sable Church, is said to recount tales that portray the suffering and conflict of Hollows." Has anyone seen the third name? Also, who are they daughters of, I wonder?
I'm also more and more convinced Gwynevere was Oceiros' Queen. Divine Blessing description:
The Queen of Lothric, married to the former King Oceiros, was initially revered as a goddess of fertility and bounty. After giving birth to Ocelotte, her youngest, she quietly disappeared.
Goddess of fertility and bounty is how Gwynevere was described in DS1. Okay, so that seems solid enough already, right? What else we got? Sun Princess Ring, found in Gwynevere's chamber.
Ring associated with Gwynevere, princess of sunlight and eldest daughter of Gwyn, the First Lord.
The ring is vaguely warm, like a beam of sunlight, and gradually restores HP.
Gwynevere left her home with a great many other deities, and became a wife and mother, raising several heavenly children.
Note the "heavenly children" bit. Divine Pillars of Light miracle:
Miracle of Gertrude, the Heavenly Daughter.
Brings down multiple pillars of light in vicinity.
The Queen's holy maiden Gertrude was visited by an angel, who revealed this tale to her.
Despite losing both her sight and voice, she was determined to record the tale. Ordinary men cannot decipher her fragmentary scrawl, nor comprehend how it became the foundation of the Angelic faith of Lothric.
"heavenly daughter" you say? Gertrude was one of Gwynevere's children. One of many, possibly. Ocelotte was simply the youngest, last to be born. Gwynevere disappeared after that, possibly because Oceiros went batshit. At the start of the fight he thinks he's holding Ocelotte, but there's nothing in his hands. Oddly though, we do hear sounds of crying as the fight progresses.
Also, Gertrude was blind and mute. She was visited by an "angel". Turn your eyes once more to that image of a Primordial Serpent with angelic wings. Gertrude couldn't see him, perhaps why she thought it was an angel? Final proof comes from Bountiful Light miracle.
Miracle taught to knights by Gertrude, holy maiden to the Queen.
The Heavenly Daughter is said to be the Queen's child.
You know who else is probably one of Gwynevere's children? The Dancer. The Dancer's Soul turns into the Soothing Sunlight Miracle.
Special miracle granted to the maidens of the Princess of Sunlight.
The miracles of Gwynevere, the princess cherished by all, bestow their blessing on a great many warriors.
Princess of Sunlight = Sun Princess = Gwynevere. Maidens are the daughters (read Gertrude's description again). What's that, you want more proof? Here you go, Dancer's Crown description:
The mirage-like aurora veil is said to be an article of the old gods, permitted only for direct descendants of the old royal family.
Dancer's Soul:
The Pontiff Sulyvahn bestowed a double-slashing sword upon a distant daughter of the formal royal family, ordering her to serve first as a dancer, and then as an outrider knight, the equivalent to exile.
You know who else is a daughter of Gwynevere probably? Rosaria. Rosaria's Soul gives the Bountiful Sunlight miracle. Also isn't it interesting that Leonhard goes to Gwynevere's chamber after killing Rosaria?
"Special Miracle granted by the Princess of Sunlight.
The miracles of Gwynevere, loved as both mother and wife bestow their blessing on a great many warriors."
I'm nor sure if Lothric and Lorian are also children of Oceiros and Gwynevere, but everything I've written above I'm pretty sure of!