He didn't disappear, he died. Whatever he found and tried to deal with, it killed him and left his two battle wizards to carry his body out of there. Alric tried to poke around there but was shooed away by the Magister Patriarch of the Gold Order.
I was about to make a post about how we don't know if he was truly killed or merely incapacitated enough to not be able to fulfill his role as Magister Patriarch anymore but I did some searching to support my argument and found a couple of bits of text I'd either missed or forgotten and didn't expect to find, ones that mention Hexensohn is "late" and therefore imply he'd dead, one of them from Algard.
Text supporting Hexensohn being dead:
for a relevant example; the Stormcast over in AoS
"Why do bad things happen to good people" is probably a much smaller and less complicated and philosophical genre of theological debate than in the real world though as it is does not have a focus on trying to reconcile the problem of evil with an omniscient, omnipotent, and omnibenevolent God of the Abrahamic variety given that gods in this setting are not omniscient(Sigmar may have been distracted by something else at the time), omnipotent(Sigmar may have had bigger stuff on his plate at the moment and had to prioritize, or omnibenevolent(Sigamrites may dispute this but that seems to be the explanation Mathilde is going with). And there are explicitly evil gods who are stronger than individuals non-evil gods so the explanation for "why did Sigmar let [some beloved family member] die?" could be the Chaos Gods did it, either indirectly because Tzeentch manipulated fate to make him trip down nine flights of stairs because they thought it would be funny and Sigmar wasn't powerful enough to stop them or more directly because a Champion of Khorne chopped his head off and Sigmar was busy doing other miracles to stop other peoples heads being chopped off and didn't have enough spare power to save [some beloved family member].
Well this is a pretty prosaic explanation for why there's always more Bugman's - the clan still exists in Karak Norn and they keep brewing more.
This is some pretty important lore that's tucked away in an adventure hook.
I guess I didn't consider the fact that he had an extensive career before Mathilde met him and was presumably save by Sigmar several times, its just that the final time when he wasn't saved by Sigmar was also the only one Mathilde was present for meaning from her point of view Sigmar's success rate for saving Abelhelm is 0%. And considering his daughter was repeatedly almost killed by Alkharad, was burning through her Greatswords, and fully expected to die before Mathilde came along and brought the best kind of good news to her, Sigmar may have been sparing Abelhelm from a perceived future of misery in favor of passing it along to his daughter, albeit a future we thankfully prevented from coming to full fruition via application of Runic Dwarven Greatsword to Ancient Vampire Neck.
I found the culprit for the DPG's Rule of Pride. Stone and Steel, page 57:
Temporary runes also originate in Stone and Steel. Also wow, Stone and Steel and 2e's Realms of Sorcery came out pretty close together: 2002 and 2005, respectively.
And using an immensely powerful runic weapon gifted to you by the dwarves to single-handedly kill the ancient undead sorcerer who was behind it all is, ironically, the most Sigmar-like way to solve a a problem.
I would argue that the Belt was more pivotal to that victory that the greatsword.
You might have a hard time imagining it but that might be hindsight talking, we would have had just as much difficulty imagining a future where we accomplished as much good as we did at the point in time after we destroyed Castle Drakenhof with Abelhelm dead as we would have had imagining a similarly spectacular future in a timeline where Castle Drakenhof was destroyed but Abelhelm lived. We're talking about extremely low probablility scenarios' here bordering on being unlikely enough to be negligible except it clearly isn't negligible considering it actually happened. With numbers so small it's hard to calculate whether the probability of such good being done was increased or decreased by Abelhelm's death. Even if Abelhelm's survival would have decreased Mathilde's chance of achieving great things it would have given Abelhelm a chance to accomplish great things too, potentially greater than Roswita did, and as long as the combined accomplishments of Alternate-Alive!Abelhelm and Alternate!Mathilde exceeded that of Our-Timeline!Mathilde that would have been a better timeline. We simply don't know and will almost certainly never know.
Yes, it is hindsight, obviously.
... no. Wtf, man.Mathilde*thinks about it*: OK, then I guess decide it is. It's just letting you rest right?
The situation is rather different when afterlife provably exists.
There are people who choose cessation of being even when there isn't one.
So is going to the toilet without a cellphone.
