A few thoughts from a veteran gamer
1) Chorae are more common than sorcerers. Their are literally thousands of chorae out there but most are in the hands of caste nobles and elite archers. They're rare, but potentially obtainable by PCs.
2) Chorae are lethal to sorcerers, but they aren't an instant win button. Chorae didn't save the guys Akka dropped a roof on, or the guys on the walls of Shimeh when the Spires blew up the walls, and more than a few Shrial Knights died when Cishaurum scourged the earth beneath their horses' hooves. There's going to need to be rules on indirect sorcerous attacks. A chorae won't save you when an earth moving cant drops smacks you with a two ton boulder.
3) This world is lethal. Sorcery blows people into smoking meat. Spectacular badasses get stabbed in the ear and die. Chorae turn sorcerers to salt. Bashrags turn people to bags of stew. Guys catch sranc javelins in the eye. Warriors like Saubon and Cnauir slaughter their way through hardened veterans.
The game's rules need to reflect that aspect of the world and provide some kind of protection for players as well. Akka, after all, isn't directly struck by the sranc's chorae. He's wounded and knocked out, but not killed. Cnauir survives the crushing defeat inflicted on his people by the Nansur due to a very generous amount of luck. Kelhous survives a Nonman unleashing deadly sorcery at close range when he first goes into the world. Something like fate points would allow players to buy down their fatal bad luck to merely incapacitating incidents or narrow escapes. That would allow the players to survive a small number of bad rolls without stacking up a massive PC body count while keeping the world dangerous to them. And, of course, if you want to increase player fatalities one need only cut down or eliminate the fate points.