Current Grimoires have no place in this game - there is little to no benefit to collecting them, and the difficulty increase is so significant that it is literally the only reason I ever fail a mission. To make it worse, a single player picking up a Grimoire penalizes the entire team - I have no control over whether or not my teammates grab this item, and yet they get to one-sidedly decide that my health gets reduced to 20-40% of its maximum.
I would personally be content to see them removed entirely, but otherwise they need some fixes.
Reward: Should either be a significant boost to money/XP, or a collection of crafting materials. Or even possibly a guaranteed “Gift from the Emperor” if both are collected. Scriptures are hardly worth picking up, and all they do is occupy your health/ammo pack slot; anything with a negative effect built in should give far more.
Negative effect: Should absolutely not affect the entire team if one player picks up an item. This mechanic is basically griefing deliberately implemented into the game. Then as a replacement effect, instead of removing a large percentage or absurd flat amount of your health and then continuing to tick away over time, it should corrupt one Wound. This would give me an excuse to use a curio that gives wounds - an otherwise useless effect to me - as well as balancing the penalty better amongst classes with differing amounts of health.