As Eno Hlaalu will tell you, "Many years ago, Black Hands Mephala made a deal with Sanguine for twenty seven tokens she could give to her devoted followers. The Dark Brotherhood stole these tokens from us, but Mephala has arranged for them to return here to Vvardenfell one by one." Your job is to retrieve 26 of these items (Hlaalu has accounted for the Amulet of Sanguine Enterprise) and return them to Mephala's service.
If you can accomplish this, you will receive the spell "Mephala's Skill," which gives 50% Cameleon for 60 seconds and Fortify Attack 10 points for 60 seconds, and your reputation within the Morag Tong will go through the roof (+25 points). If you accept promotion to Grandmaster before recovering all 26 items, you're hosed. Once Hlaalu is gone, there is no one to whom you can give them.
To help you along, most of these items are in the hands of Dark Brotherhood agents or Mephala worshippers, who will gleefully attack you on sight (that's what they do, I guess). A few of the items, however, are in the hands of relatively peaceful NPCs who you will have to Taunt into attacking you or figure a way to do the deed such that no alarm is raised.
Items that you pick up as part of writ or special duty quests are in normal type. Items in the hands of peaceful characters are in bold, and items that you will have to find on your own have a blue background.
You will pick up most of these items as part of Morag Tong Writs or as "Special Duties" from the Grandmaster and you'll probably stumble across a couple others while exploring. But here's the complete list:
|Belt of Sanguine Balanced Armor||Fortify Medium Armor||Relas Arothan||Assernerairan (Underworks, St. Olms Canton -- he'll attack you, along with Durus Marius)|
|Belt of Sanguine Deep Biting||Fortify Axe||Relas Arothan||Assernerairan (Underworks, St. Olms Canton -- he'll attack you, along with Durus Marius)|
|Belt of Sanguine Denial||Fortify Block||Movis Darys||Ald'ruhn, Mages Guild (one of the two guys downstairs)|
|Amulet of Sanguine Enterprise||Fortify Mercantile||no one||exists, but has not been placed in the game -- Hlaalu does not expect you to retrieve it|
|Belt of Sanguine Fleetness||Fortify Athletics||Hrordis||Pelagiad, Halfway Inn|
|Ring of Sanguine Fluid Evasion||Fortify Unarmored||Severa Magia||Ald Sotha (northeast of Vivec)|
|Amulet of Sanguine Glib Speech||Fortify Speechcraft||Shotherra||Thongar's Tradehouse, Khuul|
|Ring of Sanguine Golden Wisdom||Fortify Alteration||Talis Veran||Ebernanit (southeast of Valenvaryon stronghold, which is east of the Urshilaku Ashlander Camp)|
|Ring of Sanguine Green Wisdom||Fortify Restoration||Gnaw Tooth||Ald Daedroth, Right Wing (you come here for the Main Quest)|
|Belt of Sanguine Hewing||Fortify Long Blade||Durus Marius||Assernerairan (Underworks, St. Olms Canton)|
|Glove of Sanguine Horny Fist||Fortify Hand-to-Hand||Guril Retheran||Vivec, Redoran Canton, Flowers of Gold Cornerclub|
|Belt of Sanguine Impaling Thrust||Fortify Spear||Gluronk gra-Shula||Sadrith Mora, Gateway Inn, North Wing|
|Shoes of Sanguine Leaping||Fortify Acrobatics||Dro'Zaymar||Vivec, St. Delyn Canton, Canal South-Three|
|Belt of Sanguine Martial Craft||Fortify Armorer||Carecalmo||Ashalmimilkala (island west of Balmora)|
|Amulet of Sanguine Nimble Armor||Fortify Light Armor||Severa Magia||Ald Sotha (northeast of Vivec)|
|Ring of Sanguine Red Wisdom||Fortify Destruction||Llandrale Varam||Ald Sotha (northeast of Vivec - you have to pass by her to get to Magia)|
|Glove of Sanguine Safekeeping||Fortify Security||Inganar||Ularradallaku (inside the Ghostfence, north of Endusal ruins)|
|Ring of Sanguine Silver Wisdom||Fortify Illusion||Earmil||Assurnabitashpi (west of Urshilaku Ashlander camp)|
|Belt of Sanguine Smiting||Fortify Blunt Weapon||Domba||Ald Daedroth, Right Wing (you come here for the Main Quest)|
|Shoes of Sanguine Stalking||Fortify Sneak||Thovasi Alen||Assarnatamat (northeast of Balmora)|
|Belt of Sanguine Stolid Armor||Fortify Heavy Armor||Mindeli Saren||Yasammidan (west of Ald Velothi, past the Dwemer Ruins - this one is not assigned, but it's in the same location as another that you are sent to retrieve)|
|Ring of Sanguine Sublime Wisdom||Fortify Alchemy||Anel Rethelas||Yasammidan (west of Ald Velothi, past the Dwemer Ruins)|
|Belt of Sanguine Sureflight||Fortify Marksman||Durus Marius||Assernerairan (Underworks, St. Olms Canton)|
|Glove of Sanguine Swiftblade||Fortify Short Blade||Severa Magia||Ald Sotha (northeast of Vivec)|
|Ring of Sanguine Transcendence||Fortify Conjuration||Llandrale Varam||Ald Sotha (northeast of Vivec - you have to pass by her to get to Magia)|
|Ring of Sanguine Transfiguring||Fortify Enchant||Llandrale Varam||Ald Sotha (northeast of Vivec - you have to pass by her to get to Magia)|
|Ring of Sanguine Unseen Wisdom||Fortify Mysticism||Erundil||Indoranyon stronghold (getting out is harder than getting in -- look for five blue candlesticks in front of a door)|