Confusion (of the highest order) about Venat and Sundering

[Lurina]

sundering doesn't kill and since hydaelyns purpose was highly specific it didnt take as much energy to work. as for it being worth it, imo yeah considering it lead to us defeating the metea.

While it's debatable if the Sundering killed the Sundered (I would argue it did, at least to the same degree as the Rejoining, since in both cases no "soul essence" is destroyed, just divided or re-assimilated at the expense of the original identity) I think they're talking about the sacrifices. People were still sacrificed to summon Hydaelyn.