The simplest approach would be to have the Daedric Princes give them as rewards, perhaps allowing for more than one quest for some of the princes (determined randomly?). A more convoluted approach might involve crafting little in-game lore-friendly quests and stories to position the artifacts for the player to find.
Creating the artifacts themselves shouldn't be too difficult, programming wise — most of them are basically magic items. Some do have odd effects — I'm not sure how that can be implemented.
They'd need some artwork to be made, but this can probably be hacked from the existing resources (and, for a change, I could help with that part of the mod — I'm a graphic designer).
And since we are at it, we could correct some of the artifacts that are already there in the game (the Mask of Clavicus Vile, for example, should be a wearable helm. And the Ring of Hircine, a ring). I'm sure there are other details that could be fixed.
EDIT: Here's a preliminary list of the artefacts, plus notes.
I tried to register the game(s) where the artefact appears: Arena (A), Daggerfall (D), Morrowind (M), Bloodmoon (B) and Tribunal (T), Oblivion (O), Skyrim (S) and Online (OL).
Redguard (AR), Battlespire (AB) or Travels (TS, TD, TSH, TO), don't have an artefacts' page in the UESP, so I can't contribute whatever may be in those. Some artefacts are listed as appearing in Legend Cards (LC), so I did mark those. There are other sporadic lore sources — I'll try to note them as adequate.
Some items are considered artefacts by the lore, but not by the UESP. I've marked them with (?).
Some of these artifacts might not make sense in Daggerfall, because of the timeframe (they may have been created or re-created at a later date, like the Master Index or Trueflame) or because of the item's history (Wraithguard is kept by Vivec, so wouldn't be seen around Daggerfall). I tried to remark these points, so that we can focus on artifacts that do make sense in D, but I haven't played Oblivion or Skyrim or ESOL (I know, I know), so please correct me if artefacts from these later games, in particular, wouldn't make sense in D.
Aetherial Crown, Shield or Staff (S) → created during S, so don't exist in D Amulet of Kings (O) → unlikely to be around, since it's around the neck of the Emperor
- Amulet of Usheeja (M)
- Apron of Adroitness (O)
- Archmage's Robes (S)
- Auriel's Bow (A: Valenwood, Skyrim, Elsweyr) (D: Nocturnal, Knightly Order) (M)
- Auriel's Shield (A: High Rock, Summerset Isle, Skyrim) (D: Knightly Order) (S)
- Ayleid Crown of Lindai (O)
- Ayleid Crown of Nenalata (O)
- Azura's Star: (D: Azura) (M)(O)(S)
Belt of Heartfire (M) → probably not for D
- BiPolar Blade (M) → This is another interesting artifact, and it'd be fun and reasonably simple to recreate it
- Bitter Cup (M) → attributed to Clavicus Vile
- Blade of Woe (OL)
- Blood Ring (M) → could be in D? When did Dagoth Gilvoth get it?
- Bloodskal Blade (S)
- Bloodthirst (S)
- Blackwater Blade (O)
- Bloodworm Helm (M)(O)
- Boots of Blinding Speed (M) → these are very fun, and I've made good use of them in M combining them with a resistance to blindness. Might be hard to replicate?
- Boots of Bloody Bounding (O)
- Boots of the Apostle (M) → Might well be around D, since they were worn by Tiber Septim
- Bow of Shadows (M) → associated with Nocturnal. Said to have been seen around many times.
- Boots of the Crusader (S)
- Chillrend (O)(S)
Cleaver of St. Felms (M) → the name suggests it may be M-specific
- Chrysamere (A: Elsweyr, Morrowind) (D: Knightly Order, Main Quest) (M)
Crosier of St. Llothis (M) → Likely M specific
- Crown of Freydis (OL)
- Crown of Nenalata (OL)
- Cuirass of the Savior's Hide (M)(AB)(O)(S) → Hircine
- Cuirass of the Crusader
- Debaser (O)
- Dawnbreaker (S) → given by Meridia
- Dawnfang / Duskfang (S) → interesting because of the dualism. Might be hard to recreate.
- Dawnguard Rune Axe (S)
- Dawnguard Rune Hammer (S)
- Dawnguard Rune Shield (S)
- Dragonbane (S)
Daedric Crescent (M) [LB) → lore says only one exists and is in the possession of a dremora lord only acessible through Magas Volar. Unless we somehow recreate the Daedric Sanctuary Amulet quest, I'd say we ditch it.
- Denstagmer's Ring (M)
- Draconian Madstone (O)
- Dragonbone cuirass (M) → ancient, seems to wander, could be in D
- Dwarven Black Bow of Fate (S)
- Ebony Blade (A: Valenwood, Skyrim) (D: Mephala) (O)(S)
- Ebony Mail (A: Black Marsh) (D: Boethia) (M) (S)
- Eleidon's Ward (M) → belonged to a Breton knight, so fits well in D.
- Escutcheon of Chorrol (O)
- Fang of Haynekhtnamet (M) → This one is interesting, and might well be around D since it «is seen with travelling heroes».
- Fists of Randagulf (M) → Very interesting to implement, since there are few other gauntlet artifacts.
- Fork of Horripilation (M) → Definitely should make an appeareance in D, perhaps with a quest similar to M.
- Gauntlets of the Crusader (S)
- Goldbrand (M) → Boethiah. It's variant Eltonbrand is a punt and probably doesn't make sense to include it.
- Gray Cowl of Nocturnal (O)
- Hair Shirt of Saint Aralor (M) → feels like a very M-specific thing
- Harkon's Sword (S)
Heart Ring (M) → since it is in the hands of Dagoth Ur, may not be around in D
- Helm of Oreyn Bearclaw (M)(O) → given by Malacath
- Helm of the Crusader (S)
- Helm of Tohan (?) (M) → what is the lore? Where does it come from? Should it be around in Daggerfall?
- Hevnoraak (S) →
- Hircine Ring (D: Hircine](M) → needs image fix
Hopesfire (M) → Probably not available in D, since it is owned by Almalexia
- Hrormir's Icestaff (O) (OL)
- Ice Blade of the Monarch (M) → Could well be in D, since lore says «circulates from owner to owner»
- Jewel of the Rumare (O)
Keening (M) → probably shouldn't be seen outside M, although it does appear in S and L.
- King Orgnum's Coffer (A: Summerset Isle, High Rock) → this would be not very useful, nor game-breaking, but fun lore-wise
- Lord's Mail (A: Skyrim, Black Marsh, Summerset) (D: Knightly Order) [M
Mace of Aevar Stone-Singer (M) → Unlikely to be around D.
- Mace of Molag Bal (D: Molag Bal) (M) → In S, people approached with the mace on hand seem to be terrified and want to get away. It'd be nice to replicate this.
- Mace of Slurring (M)
- Mace of the Crusader (S)
Master Propylon Index (M) → Since it is created in M, shouldn't exist before
- Masks of the Dragon Priests (many) (S)
- Masque of Clavicus (D: Clavicus Vile) (M)(O)(S) → needs fix (it's a ring, but should be a helmet)
- Mehrune's Razor (D: Mehrune's Dagon) (M)
Miraak's Boots, Gloves, Robes, Sword & Staff (S) → If they weren'y created by Miraak, they should probably all be renamed.
- Mentor's Ring (M) → circulates around, could be in D
- Mnemic Egg (OL) ???
Moon-and-Star (M) → Most definitely *not* in D Muatra (OL) and mentioned in (M) → in possession of Vivec, so shouldn't be in D.
- Necromancer's Amulet (A: High Rock, Summerset Isle) (D: Knightly Order, Main Quest) (M)
Nerveshatter (S) → created in S, so not in D.
- Nightingale Blade (S) → could possibly exist in D
- Nightingale Bow (S) → could possibly exist in D
Odd Dwemer Weapon (M) → unlikely to be around D, since it's in the hands of Almalexia.
- Oghma Infinium (A: Skyrim, Elsweyr, Morrowind, Black Marsh) (D: Hermaeus Mora)
- Ring of Eidolon's Edge (O)
- Ring of Khajiit (A: Hammerfell, Valenwood, High Rock) (D: Meridia](M)
- Ring of Namira (D: Namira)
- Ring of Phynaster (A: Summerset Isle, Elsweyr, Black Marsh, Skyrim)(M)
- Ring of Sunfire (O)
- Ring of Surroundings (M) → might be around in D. Used by the empire as a reward for things discreetly done.
- Ring of the Wind (M) → Sacred to Kynareth
- Robe of the Lich (M) → Another interesting artifact. It'd be worthwhile to recreate it.
- Rueful Axe (S) → given by Clavicus Vile
- Ruin's Edge (S) → another fun artifact (randomness always adds spice)
- Rugdumph's Sword (O) → wouldn't probably have this name, but might already exist in D if Rugdumph got it second-hand
- Sanguine Rose (D: Sanguine)
- Scourge (M) (AB)
- Shadowrend (S)
- Shield of the Crusader (S)
Shield of Ysgramor (S) → since at S is still in its original resting place, unlikely to be found around D Shoes of St. Rilms (M) → feels like a very M-specific thing
- Skeleton Key (A: Valenwood, Summerset Isle) (D: Nocturnal) (M)(O)(S)
- Skull of Corruption (D: Vaernima)
- Skull Crusher (M) → lore literally says «it still travels Tamriel», so could be in D
Soul Ring (M) → owned by Dagoth Araynys. Smells like it was a reward from Dagoth Ur, so probably not likely seen outside the Sixth House
- Spear of Bitter Mercy (M)(AB) → Hard to implement: no spears in D.
- Spear of the Hunter (M) → Interesting, bur hard to implement: no spears in D.
- Spell Breaker (A: Hammerfell, Valenwood) (D: Peryte) (M)(O)(S)
- Spelldrinker Amulet (O)
- Staff of the Everscamp (O)
- Staff of Hasedoki (M) → another one which «travels tamriel»
- Staff of Indarys (O) (OL)
- Staff of Magnus (A: Elsweyr, Valenwood) (D: Knightly Order) (M)
- Staff of Sheogorath (S)
Staff of St. Llothis (OL) → Feels M-ish in name Staff of Worms (O) → probably shouldn't be accessible yet, as of D's events
- Stendarr's Hammer (M)
- Sunna'rah (OL) → created by Sotha Sil, but when?
Sunder (M) → I assume this would *not* be around D
- Sword of Jyggalag (S)
- Sword of the Crusader (S)
- Targe of the Blooded (S)
- Ten Pace Boots (M) → possibly associated with Sheogorath?
- Thornblade (O)
Trueflame (M) → unlikely to be around D, since it hasn't been reforged yet.
- Ul'Vor Staff (OL)
- Umbra Sword (M)(O)(S)(LC) and «features in Greg Keyes's novels The Infernal City and Lord of Souls» (which I have not read). It seems to be always carried by a character named Umbra (in M an orc, in O a bosmer). The sword itself was created by Naenra Waerr, «an ancient witch», so might already be around in D. Might be fun to link it to an orcish character, perhaps as a sidequest to dealing with the orcs in D. There's ample lore about it in the UESP.
- Vampiric Ring (M) → Lore says it was created «long, long ago» by vampire followers in Morrowind, and seen very rarely. Still..
Veloth's Judgement (M) → the name suggests it is M-specific
- Volendrung (A: Hammerfell, Morrowind) (D: Malacath)
- Wabbajack (D: Sheogorath) (M)
- Ward of Akavir (M) → could be replicated with any shield, really
- Warlock's Ring (A: Morrowind, Elsweyr) (D: Knightly Order, Noctunral, Main Quest) (M)
- Weatherward Circlet (O)
- White Phial (S) → anoter fun one. It could be implemented as a potion which replenishes itself every 24h and provides any desired potion's effect. Probably feasible.
- Wings of the Queen of Bats (M) → never implemented. Does it have lore?
- Witsplinter (O)
Wraithguard (M) → Should probably not be seen outside M. Wuuthrad (S) → the axe is fragmented at the beginning of S, so it shouldn't perhaps be in D