Feats are a fundamentally garbage means of assessing this kind of thing. Taking feats as sacrosanct is the kind of shit that leads to superhero vs debates where the Flash can at the same time think and react in attoseconds, yet also gets tripped up by Deathstroke sticking a foot around a street corner three times in the same issue.
It is far, far more fruitful to consider these things in the context of the wider narrative they sit in, and that requires acknowledging that, for example, necromancy in warhammer has a strong trend of development over time as wizards like Van Hel iterated on Nagash's discoveries, and that Nagash's story is one of a great threat long past at his height, when he did great things from a position of partial rulership over Khemri and the advantages that came with it, but who was lessened and beaten down the ages. Meanwhile Kemmler's story is a much more recent one of a genius prodigy at this vile art who terrorised the land with a mastery of the black arts that built on and superceded all who came before.
Thing is those narratives don't seem like in anyway a given or natural reading of the source material, and that's even discounting EoT. For one where in the army books or any material is it ever written that Kemmler surpassed Nagash as the one superceded "all who came before". Similarly you seem to make a lot of one spell having the name of one necromancer other then Nagash. I could just as well point out to how necromancers centuries and even millenia past Nagash still obsessively cling to his creations and books long, long after the Great necromancer has past. See for example Vlad with his ring and book of Nagash.
If you have more fun viewing Nagash as the threat long past, as the teacher who had long since been surpassed by his students then by all means, I'm not one to gainsay what makes the game more fun for others, but that doesn't strike me as either a given or even a likely reading of the source material.
Heck even the High Elves' own army books attempts to give Teclis' own prowess high praise by comparing him to Nagash and not, for example, Kemmler.
Nope. Aenarion and Indraugnir fought four greater daemons at once; even if we assume Indraugnir is worth two himself, that still leaves Aenarion throwing down with two greater daemons and winning. He also didn't die in the process; he was sorely wounded, but he limped away from that fight with enough strength to fly half the length of Ulthuan and walk from the shores of the Blighted Isle to the Shrine of Khaine at their heart. (He might also still be alive - he's assumed to be dead because he never turned up since, but they never did find a body, and you know what that means with dramatically significant people...)
And yeah, if you stripped him of his panoply and mauled him, he'd be a lot less of a threat. The same is true of Sigmar though, and frankly, even in bare-handed wrestling, Aenarion would cream Sigmar. One's an anointed superhuman demigod who slew a daemon lord with a single throw of a hunting spear, the other's a mortal human. A very buff and skilled mortal man, the guy's a Conan expy, but he wasn't superhuman. That is, again, the point of Sigmar; he was a man before he was a god.
When making that equivalence I was referring to how Nagash was without gear, down a hand and weakened by his resurrection when he fought Sigmar, being down all of his gear, down a hand and weakened by his resurrection and even then Sigmar needed Nagash's own creation, the crown, to beat him.
Also Sigmar has accomplishments such as fighting against a named daemon of Khorne, Skulltaker, for three days without rest and winning, scaling the Ulricsberg, going through the flame of Ulric and coming out unburnt and more that cast serious doubt on him not being superhuman. I'd say it's even hard to imagine how someone who wasn't superhuman could possibly win against an Everchosen even with Ghal Maraz. Chaos Lords are explicitly and blantantly superhuman and the Everchosen is the most powerful of them all, with Archaon having accomplishments such as strangling a bloodthirster to death with his own whip. Even with Ghal Maraz it's hard to imagine how someone could avoid being killed, let alone win, against such a foe via the superhuman Chaos Lord killing them so quickly they wouldn't even have time to lift Ghal Maraz.
Either way the original point was that reducing the defeat of even a much weakened Nagash to Sigmar as Nagash "getting his teeth kicked in by a guy with a very shiny hammer" ignores how that guy with a shiny hammer also has a history of inflicting such defeats on some of the other most powerful characters in Warhammer.
