http://esoacademy.com/set-bonus-items/

http://esoacademy.com/news/one-tamriel-dueling-item-changes-weapon-ultimates/

Had been asking the same question, then google found these

This is a fantastic addon so you don't need to leave the game to look : http://www.esoui.com/downloads/info1480-ItemizationBrowserOneTamriel.html

Or there's a spreadsheet here: https://forums.elderscrollsonline.com/en/discussion/comment/3360481/#Comment_3360481

ookami007 wrote: »

Is there a list out there of where each of the new overland, monster, dungeon, etc sets can be found?

yes in the Patch Notes: https://forums.elderscrollsonline.com/en-GB/discussion/294849/pc-mac-patch-notes-v2-6-4-update-12-one-tamriel#latest

Item Set Drop Locations
Many drop locations for Item Sets have been changed. Below are the locations for all existing and new Item Sets (generally listed in Light/Medium/Heavy order when applicable).
Overland
Alik’r Desert: Robes of the Withered Hand, Sword-Singer, Order of Diagna
Auridon: Queen’s Elegance, Twin Sisters, Armor of the Veiled Heritance
Bangkorai: Vampire Lord, Spriggan’s Thorns, Seventh Legion Brute
Coldharbour: Prisoner’s Rags, Stygian, Meridia’s Blessing Armor
Craglorn: Way of Martial Knowledge, Way of Air, Way of Fire
Deshaan: Mother’s Sorrow, Night Mother’s Embrace, Plague Doctor
Eastmarch: Stendarr’s Embrace, Fiord’s Legacy, Akaviri Dragonguard
Glenumbra: Bloodthorn’s Touch, Hide of the Werewolf, Wyrd Tree’s Blessing
Gold Coast: Sithis’ Touch, Flanking Strategist, Hide of Morihaus
Grahtwood: Syrabane’s Grip, Ranger’s Gait, Green Pact
Greenshade: Shadow Dancer’s Raiment, Wilderqueen’s Arch, Beekeeper’s Gear
Hew’s Bane: Bahraha’s Curse, Syvarra’s Scales
Malabal Tor: Spinner’s Garments, Salvation, Thunderbug’s Carapace
Reaper’s March: Skooma Smuggler, Senche’s Bite, Soulshine
Rivenspire: Necropotence, Darkstride, Vampire Cloak
Shadowfen: Robes of the Hist, Swamp Raider, Hatchling’s Shell
Starter Areas (Khenarthi’s Roost / Stros M’kai, Betnikh / Bleakrock Isle, Bal Foyen): Armor of the Trainee
Stonefalls: Silks of the Sun, Coat of the Red Mountain, Shalk Exoskeleton
Stormhaven: Dreamer’s Mantle, Night Terror, Storm Knight’s Plate
The Rift: Ysgramor’s Birthright, Witchman Armor, Draugr’s Heritage
Wrothgar: Trinimac’s Valor, Briarheart, Mark of the Pariah
Dungeons
Arx Corinium: Lamia’s Song, Undaunted Infiltrator, Medusa
Banished Cells: Sanctuary, Jailbreaker, Tormentor
Blackheart Haven: Undaunted Unweaver, Bone Pirate’s Tatters, Knight-errant’s Mail
Blessed Crucible: Noble Duelist’s Silks, Sword Dancer, Nikulas’ Heavy Armor
City of Ash: Burning Spellweave, Sunderflame, Embershield
Cradle of Shadows: Gossamer, Widowmaker, Hand of Mephala
Crypt of Hearts: Shroud of the Lich, Leviathan, Ebon Armory
Darkshade Caverns: Netch’s Touch, Strength of the Automaton, Armor of True
Daily Dungeon Reward: Willpower, Agility, Endurance
Direfrost Keep: Magicka Furnace, Draugr Hulk, Ice Furnace
Elden Hollow: Light Speaker, Barkskin, Undaunted Bastion
Fungal Grotto: Spider Cultist Cowl, Viper’s Sting, Dreugh King Slayer
Imperial City Prison: Scathing Mage, Sheer Venom, Leeching Plate
Ruins of Mazzatun: Amberplasm, Heem-Jas’ Retribution, Aspect of Mazzatun
Selene’s Web: Vestments of the Warlock, Hircine’s Veneer, Durok’s Bane
Spindleclutch: Prayer Shawl, Spelunker, Knightmare
Tempest Island: Overwhelming Surge, Storm Master, Jolting Arms
Vaults of Madness: Worm’s Raiment, Oblivion’s Edge, Rattlecage
Volenfell: Treasure Hunter, Crusader, Duneripper’s Scales
Wayrest Sewers: Combat Physician, Toothrow, Sergeant’s Mail
White-Gold Tower: Spell Power Cure, Essence Thief, Brands of Imperium
Trials
Aetherian Archive: Healing Mage, Quick Serpent, Defending Warrior
Hel Ra Citadel: Destruction Mage, Poisonous Serpent, Berserking Warrior
Maw of Lorkhaj: Twilight Remedy, Moondancer, Roar of Alkosh, Lunar Bastion
Sanctum Ophidia: Wise Mage, Twice-Fanged Serpent, Immortal Warrior
Aetherian Archive / Hel Ra Citadel / Sanctum Ophidia: Infallible Mage, Vicious Serpent, Eternal Warrior
Arenas
Dragonstar Arena: Healer’s Habit, Robes of Destruction Mastery, Archer’s Mind, Footman’s Fortune
Maelstrom Arena: Elemental Succession, Winterborn, Hunter Leader, Permafrost, Glorious Defender
PvP
Cyrodiil: Affliction, Alessian Order, Almalexia’s Mercy, Arch-Mage, Bastion of the Heartland, Beckoning Steel, Buffer of the Swift, Crest of Cyrodiil, Curse Eater, Desert Rose, Elf Bane, Fasalla’s Guile, Hawk’s Eye, Juggernaut, Kyne Kiss, Leki’s Focus, Light of Cyrodiil, Marksmen’s Crest, Morag Tong, Ravager, Robes of Alteration Mastery, Robes of Transmutation, Sentry, Shadow Walker, Shield of the Valiant, Vicious Death, Wary of Cyrodiil, Warrior’s Fury
Imperial City: Black Rose, Galerion’s Revenge, Imperial Physique, Meritorious Service, Phoenix, Powerful Assault, Reactive Armor, Shield Breaker, Thews of the Harbinger, Vicecanon of Venom

Oh for the good old days pre-internet, when such questions would be answered with the aid of one's own pen and paper !