I mean, forgive me if I’m wrong, but I thought it was always explicitly stated that the Nathrezim created Frostmourne and Kil’Jaeden turned Ner’zhul into the Lich King.
Is this just Blizzard retconning old lore again to stuff square pegs into round holes?
Spoiler: Maybe not .
https://www.youtube.com/watch?v=3ylPL5jzHYA
TL;DR
Burning Legion was used by Sire Denthrius who might be the true masters of the Dreadlords. Basically, vampires made a pro gamer move.
“Nathrezim”
Castle “Nathria”
Coincidence? I think not.
TL;DW for those of us who don’t want to mash that like and subscribe button, and check out their other videos?
Apparently Dreadlords originated from Revendreth so it’s not entirely false.
added TL;DR in the spoiler
Retcon bro Retcon
I mean it is easier to say that you made something than it is to explain how you managed to not only transcend the barrier between life and death but also return with a sword and a fancy hat of all things.
wow dude spoilers
It was literally shown in the Bastion trailer.
sarcasm goes over your head huh?
It was once upon a time. Then it got retconned.
There was nothing in your statement that appeared to be sarcasm.
To be fair… the lore surrounding everything with the undead in WoW is very muddled and filled with retcons and contradictions… The plague was a creation of Fel magic… undead were originally said to be made through Shadow magic… necromancy wasn’t its own thing until after WoW launched… in Vanilla Undead still has the Shadow magic origin…
What’s a few more plot holes added to a page full of them going to hurt…
In Warcraft 3 it was made clear that the origins of the Scourge were the Legion, so necromancy was still a weapon of the demons.
If only WC Reforged added all the retcons/new lore to align it with WoW.
Sigh
Well given that the entire Shadowlands themselves just popped up out of nowhere with new Titan+ races and entities all completely unforeshadowed, I’ma gonna go with retcon.
It just makes some of the events of WC3 make little logic.
The existence of Ner’zhul as the Lich King makes no logistical sense. It’s now pretty obvious that Kil’Jaeden didn’t make the Lich king, he dismembered Ner’zhul but the helmet and the sword were most likely made/stolen/used by the Dreadlords, so it was the dreadlords that pieced Ner’zhul together to be used as a factory to mass produce foot soldiers.
Aren’t dreadlords supposed to be super intelligent? Why would they give away a weapon that can literally end the world when they had no real control over its wielder? Why didn’t they just use the sword themselves? Ner’zhul wasn’t a necromancer in life, so it’s pretty much implied that he gained the knowledge to dominate the dead only because they gave him the Helm and the sword.
Why would Kil’Jaeden and the dreadlords entrust the very creature they tortured and killed with a worldbreaking weapon? Possibly even a universe ending weapon. The dreadlords were completely oblivious to the machinations of Ner’zhul and Arthas for the entirety of WC3.
Yes, but necromancy (death magic) wasn’t defined as its own force until later. At that time necromancy was defined as a part of Shadow magic. During WC3 we had Light, Shadow, Fel, Arcane, and Nature… Nature wasn’t a subsect of Life and Necromancy was a subsect if Shadow… the categories of Life and Death magic didn’t exist at that time in Warcraft lore… things got retconed sometime after WoW launched to add Death and separate Necromancy from Shadow, and at the same time turned Nature to a subsect of the newly added Life magic to oppose Death… this retcon was made simply because 6 cosmic forces each opposing another works better in world building than 5… though the system with 5 did still work, as Nature was originally at the center and acted as a balance to the other 4…
In WC3 the scourge was indeed created by the Legion… Mal’ganis used Fel magic to concoct the plague to convert the denizens of Azeroth against their will. Presumably combining his skill with shadow magic (as a Nathrezim) with Fel magic when doing so… Seeking to create mindless pawns out of the races of Azeroth rather than true demons.
Shadow magic was actually not included in the Warcraft mythos until World of Warcraft came out. By the time of Warcraft 3, the only magics involved in the universe were the Light, Arcane, Fel and Nature, and even then they were only loosely defined as there was no actual need to differentiate the magic types except for cosmetic and lore purposes.
Necromancy had been introduced to Azeroth via the invasion of the Burning Legion during the War of the Ancients, when the Legion used the night elven dead to bolster their own forces and demoralize the resisting armies, as seen in the War of the Ancients trilogy.
In fact, the only two practitioners of necromancy that we’re aware of that didn’t have direct ties to the Burning Legion are the ancient Mogu and Hakkar the Soulflayer.
From the datamined book/letter thing… it seems like the Dreadlords aren’t really working for anyone but Sire Denathrius, and have been infiltrating or spying on the various other cosmic forces in the universe. Really makes you take a much harder look at Lothraxion.
I suggest watching this video:
So to answer you:
the sword were most likely made/stolen/used by the Dreadlords, so it was the dreadlords that pieced Ner’zhul together to be used as a factory to mass produce foot soldiers.
This is correct.
Why would Kil’Jaeden and the dreadlords entrust the very creature they tortured and killed with a worldbreaking weapon?
Kil’jaedan wouldn’t… but the Dreadlords would since they seem to actually be double agents working for Sire Denathrius and only posing as agents of the Legion (and possibly the Army of the Light in the case of Lothraxion).
The dreadlords were completely oblivious to the machinations of Ner’zhul and Arthas for the entirety of WC3.
I’m sure they wanted it to seem that way… 
Here’s the item for you to read the text:
https://shadowlands.wowhead.com/item=183742/enemy-infiltration-preface