Originally Posted by
Absimiliard
The Warrior of Light is explicitly shown to be an exceptionally well-learned and traveled individual, and an excellent storyteller to boot. While it is impossible for the WoL to have known everything, there is a significant amount of information they come across over the course of the game's story. The WoL does understand the mechanics and requirements behind Calamities and Rejoinings by the time you go to Elpis. While you are correct in assuming they wouldn't know every Calamity down to the detail, they would have a very good general idea of when the (by their perception) most recent ones took place as well as which element each required the scales tip toward.
Factor in everything else the WoL knew by that point, and Venat is suddenly rather well forewarned as to things to come. If nothing else, it's plenty enough information for her to recognize signs of Ascian BS and thus be able to take action preemptively when they're setting the stage for a Calamity.
What I wonder isn't even about Calamities and the like. What I'm curious about is if the WoL bothered to tell her about all the non-Ascian-related suffering, sorrow, and death people from their time endure on the regular. Her seeming hard lean into "suffering is good" leads me to rather strongly suspect this was indeed amongst the information passed along, though I don't think Venat knew just how bad it was going to be until she saw it with her own eyes. Even the best of storytellers cannot convey such misery with words, after all. Only by seeing, if not experiencing, can one truly grasp the scope of sorrows inflicted by mortality and its frailties.