^Basically.
They are not OP at all. They have a bit of an edge because of some enhancements & magic as they are both DEMONDAL addicts as well but that's it. Kei can use a sword when he needs to be but he's an Archer first & foremost.
It is "needlessly realistic". Get poisoned & you'll most likely drop right there & suffer before dying, get injured in an arm & you won't be able to use it in battle anytime soon, etc.
There are (rare & expensive) healing potions but