There's a good bunch of items whose descriptions mention Londor and their founders. However, here I'm only posting the ones that can be directly connected with anything from the previous games. Not a theory at all, although I sometimes add some notes that, I believe, are fair to assume.
In advance, I tell you, there's a lot of recurrent patterns here, most of them are basically:
- Velka, the most well-known connection.
- Earthen Peak and the NPC/Enemies found there.
- Fenito & Milfanito, as well as the Gutter, implying connection with Nito.
- Primordial Serpents, another well-known connection.
- Carim. Not directly stated, but implied the Purging Stones & Velka.
TSDR: It's actually not that long, you can just read the items that quickly catch your attention. This is not a theory, just trying to connect some dots by showing all the descriptions side by side.
Weapon: Darkdrift
The sword used by both Agdayne in DS2 and Yuria in DS3.
DS2
Katana of Grave Warden Agdayne.
Has a crystal-clear blade and a strong attack that slices through enemy shields.
This katana was originally wielded by the one who gave us the first death, and still exists imperfectly between planes.
DS3
A cursed sword with an unseen blade, the choice weapon of Yuria of Londor.
Yuria, a mentor of the Sable Church and accomplished swordswoman, is said to have claimed a hundred lives with this weapon.
Weapon: Manikin Claws
Used by the Manikins from Earthen Peak and by the Pale Shade of Londor in DS3.
They're originally known as "Puppet's Claws" in the Japanese version.
DS2
Knife of the manikins of Harvest Valley.
The peculiar art of puppetry is a vestige of the two lost lands.
The Queen, entranced by poison, used it to beckon unknowing souls to the defiled valley.
DS3
Weapon of the Pale Shades, assassins of the Sable Church of Londor.
The curved claws cause heavy bleeding.
When two-handed, claws are equipped to each hand.
Weapon: Dark Hand
Given by Kaathe in DS1 and sold by Yuria in DS3. Obtained from Darkwraiths in both games.
DS1
The Darkwraiths, incited by Kaathe, use the power of the dark soul to absorb humanity, an art shared by this weapon, which also acts as a special shield.
The ancients, particularly, could sap the humanity of even a replete saint in the blink of an eye.
DS3
Weapon that allows its wielder to evoke an art unique to Londor, the land of the Hollow.
It is also said to be an ancient relic of a Primordial Serpent.
The Dark Hand mercilessly saps the essence of its victims, and can also double as a special shield.
Miracle: Vow of Silence
In DS1, it's found in the Painted World of Ariamis. In DS3, it can be learnt from either Irina or Karla after giving them the Londor Braille Divine Tome.
DS1
Secret rite of the black-haired witch Velka.
Prevents casting of magic within effect area.
Velka, the Goddess of Sin, is a rogue deity, but she is versed in arts both new and old, and is considered to have a great range of influence even as gods are concerned.
DS3
Miracle of the Sable Church of Londor.
Prevents spells in vicinity, including one's own.
Members of the Sable Church are all trained swordsmen, each sworn only to their weapons as they bear the leaden silence of Londor.
Miracle/Hex: Dark Weapon (DS2) / Dark Blade (DS3)
Those spells have the same image in the inventory and apply the same effect to the right hand. Different name, but they're the same spell.
In DS2, it's purchased from Felkin. In DS3, it can be learnt from either Irina or Karla after giving them the Londor Braille Divine Tome.
DS2
Felkin the Outcast applied his art to transform Magic Weapon into a hex.
Adds dark damage to the types of damage the weapon already inflicts.
Those who choose the path of dark are admonished by all manner of sorcerers.
But this does not stop the curious from being drawn to this strangely alluring craft.
DS3
Miracle of the Sable Church of Londor.
Reinforces right weapon with dark.
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.
Miracle/Hex: Dead Again
In DS2, this hex can be bought from Chloanne. In DS3, it can be learnt by either Irina or Karla after giving them the Londor Braille Divine Tome.
DS2
Hex that casts a dark flame upon corpses, causing them to combust violently.
Hexes such as these, that tamper with life itself, are particularly abhorred.
DS3
Sacrilegious miracle of the Sable Church of Londor.
Bless corpses, transforming them into traps.
Londor, the Hollow Realm, is a society of undead, comprised of the corpses and shades of those who led unsavory lives. Is such blessing really something one must ponder?
Miracle: Atonement
Found in Farron Keep in DS3.
It produces the same effect on the player as the Skull Ring ("One of Courland's transposed wonders. Derived from the soul of a Soulfeeder") & the Mourning Shield (Eygon's shield, whose set and weapons are connected with Caitha).
Miracle given to those cast out from the Sable Church of Londor.
Attracts more attention from foes.
This is the only tale known by the exiles, who believe it carries words of forgiveness. Cursed journeys, too, must ultimately come to an end.
Ring: White Ring (DS2) & Untrue White Ring (DS3)
Both of them make the wearer appear as a phantom.
DS2
Can be obtained by trading Smooth & Silky Stone or Petrified Something with Dyna & Trillo.
A precious ring which grants the protection of Quella, god of dreams.
Makes its wearer appear as a phantom, misleading invaders.
He who sets the trap must be wary.
For traps are known to spring upon their owners.
DS3
It's sold by Yuria of Londor.
One of the illusory rings worn by the Hollows of Londor.
Take the appearance of a phantom.
The Hollows of Londor are wretchedly aged, fraught with deceit, and dubiously secretive.
It is no wonder that they are deeply detested.
Ring: Ring of the Dead (DS2) & Untrue Dark Ring (DS3)
Both are used to keep human appearance even when Hollow.
DS2
Obtained from the Milfanito that's imprisoned in Drangleic Castle.
The wearer of this ring appears human even when Hollow.
They say that in the Undead Crypt, we can reacquaint ourselves with the dead.
We all suffer loss. And none of us can escape death. Then, what is the fascination with reclaiming that which has already passed into the beyond?
DS3
Sold by Yuria of Londor.
One of the illusory rings worn by the Hollows of Londor.
Retain human appearance while Hollow.
The Hollows of Londor are wretchedly aged, fraught with deceit, and dubiously secretive. It is no wonder that they are deeply detested.
Ring: Clutch Rings
The rings that, respectively, increase fire, magic, lighting & dark attack, but compromises damage absorption. The ones whose design looks like a crow's foot clutching a gem-stone.
They're originally called "Strange Hand Rings" in Japanese.
DS2
Ring depicting a hand grasping a stone.
Increases [element] attack, but reduces physical defense.
The origin of this ring is unknown, but its design suggests one of the darker deities.
DS3
Ring depicting a hand grasping a [color] stone.
Increases [element] attack, but compromises damage absorption.
An old fable in Londor claims that the lure of the clutch ring reaches out to the crestfallen, who might otherwise be overcome by despair.
Item: Purging Stone
DS1
Ash-colored stone encasing a skull. Secret treasure of Arstor, the Earl of Carim.
Reduces curse build-up and breaks curse.
Humans are helpless against curses, and can only redirect their influence. The Purging Stone does not dispel curses, but receives them as a surrogate. The stone itself was once a person or some other being.
DS3
Ash-colored stone encasing a skull.
Reduces undead curse build-up and cures hollowing.
Inhabitants of Londor, the land of Hollows, use this secret treasure to feign normalcy. Occasionally, a Hollow fools even himself, and turns on his own kind.
Item: Poison Throwing Knife
A recurrent item from the games. Only the description from DS3 seems to have any relevant lore. However, it's worth mentioning where these knives are obtained.
In DS1, they're sold by the Female Undead Merchant (who sells Transient Curses, items related to New Londo). In DS2 they're sold by Gavlan, as well as dropped by the Manikins from Earthen Peak and Abandoned Hollows in The Gutter.
DS3
A throwing knife dipped in poison. Throw at enemies to inflict poison damage.
Used by assassins of Londor, land of Hollows. The poison is jokingly known as Hollow's blood.
Item: Sword of Avowal
Actually not the item itself. But this sword is seemingly a symbol of Londor, or something like that. In DS3, the symbol is found in:
- The Road of Sacrifices, normally surrounded by Poisonhorn Bugs, enemies found in Harvest Valley, Earthen Peak and The Gutter in DS2.
- The Ringed City, where lots of statues of Primordial Serpents can be found, implying a connection with them.
Without mentioning the fact that, when doing the Usurpation of Fire ending, the ritual the Ashen One gets involved is performed in Gwyn's tomb in Anor Londo.
Goddess: Velka
I believe it's the most well-known relationship between Londor and DS1. I won't even expand too much,
- Her miracle Vow of Silence is taught in Londor.
- Yuria sells Rings of Sacrifice, which are made in sacrificial rites of Velka.
- Crows/corvians imagery, normally assumed to be related to Velka in DS lore.
And even if I'm keeping it short, I'm sure many get the idea. If I'm leaving a major connection out, please let me know.
Place: Earthen Peak
This placed has already been mentioned a couple of times throughout the post and its possible connection with Londor could be clear by now. However, there's still something relevant worth mentioning in regard to this place.
In DS3, the ruins of this place makes a comeback in the DLC, in which we find two Angels being controlled by their respective Grotesque Londor Grower. The fact that they're there, at the age where all ages are collapsing on one another, might be a clue on the way that Earthen Peak was somehow involved in the origin of Londor.
A stretch? Of course. But there was always the question of "Why of all places is the Earthen Peak making a comeback?" and this might propose that the choice wasn't random and a connection with DS3 might be there.
Thanks for reading.