Would be cool to remove the one-hit kill running enemies. It's no fun when the screen is filled with enemies then that fat lady come running like there's no tomorrow and instantly kills one of your allies. If the 1-hit kill enemies walk slowly, you at least have how to spot them and dispose of them before you lose everyone at your side.
Another thing, try to balance this better or at least remove that 'you keep nothing if you lose'. Doing a 50 area quest to reach the final boss and see the thing one-shot your whole party just to realize all your time was worth nothing isn't fair. It's OK to be hard, but giving that feeling you get after you typed your school's homework and get an energy outage seconds before you click that save button... c'mon.
The idea is good, but...
a. Instead of those locked companions you get from time to time, why not make it possible for them to levelup with you and let you change their equipment and even class. Take example from the game 'Sands of the Coliseum' where you can either invest and level an ally or acquire better ones along the road if you wish.
b. Too much grindfest. Grindfest doesn't add to the game's length like you the author seens to think.