Somna I lean towards that sentiment. Chorae being all or nothing is something that makes Earwa unique, and changing that could be too much.
I suggest allowing for some kind of find-and-disarm mechanic. For example, if two groups are facing a boss with a chorae, the schoolmen might spend his turns "feeling" where exactly the hidden chorae is. One he is successful, the other members of his group could try to target that spot and try to get the opponent to drop it.
Also, the schoolman wouldn't be totally useless. He might be able to search the surroundings and look for rooks, or loose walls/cieles/tree branches that could be lifted and thrown at the enemy, doing some amount of damage, hindering or disorienting them in some way, etc. I think we will need to find out of the box solutions for this, and therefore account for them when building our world here.
Damage values for inanimate objects based on size/weight and distance from target.
Ability for schoolman to move/lift/throw based on school, rank, and experience and even specific skills?
Think of things like creating a dust storms in a desert to blind enemy
Use schoolmen to create armors from mundane materials (must be recast every battle), good for absorbing 1 blow from a choraed opponent, used on self or companions.
In order to stay true to Earwa, we will have to invent plausible scenarios that might offer a balance to make things more palatable for the player, or at least playable and worth the risk
Also, as long as there is not skin to chorae contact, the schoolman would survive. Hurt, certainly, knocked-out, probably, but at least still alive.