I assume that the 10% (potentially 2% in future) only applies when you get your companion "fully-wounded" - unable to take further part in combat.
Certainly you don't mean a 10% chance in each battle?
BTW - I'm with Tierre on this. It is ridiculous to price the development time and costs of companions so high if the devs' plan is to make them die. (MAKE them die? Yes! A full campaign involves hundreds of combats and even a 2% chance will see off your carefully-chosen-and burnished companions eventually.)
Hey, if you're going to do that, at least give players an option to turn it off
Hey again, I just decided to stop playing until this is sorted out. I don't care to lose my investment in my companions.