Undoubtedly, this is already a very interesting system, but it still has a lot to grow. And here are a few of my suggestions (there will be no suggestions on balance and so on, rather to play the role of your favorite archetype).
1. Allow you to choose more types of attacks for the grimoire (by type of fire damage, electric or frosty). In my opinion, restricting a player in such a seemingly diverse system is very disappointing and does not allow them to fulfill all their desires. For example, on release, all spells of soul grimoires could have electric damage, but could not have ice or fire damage (but fortunately in update 43 this was fixed, and now ice is also available). The same applies to the grimoire of the Guild of magicians. Electric damage is not available in it. I understand that sometimes some types of attacks are blocked, for the sake of balance (pulling or knocking down), or to be logical (the torch grimoire has fire damage available, but no ice or electric damage (although I think it would be fun to beat everyone with a ice torch)). So, in simple terms, let the grimoires have as many types of attack as possible, as long as they do not contradict the balance (Fire, Poison, Ice, Lightning). I think these types of attacks will suit all grimoires, and there's no point in not adding them to them.
2. The type of attack is plants. before you ask why, I'll tell you - for the sake of playing your role. What's wrong with your spell having the same visual effects as warden's. You will be able to play the druid class without even being a druid. I do not know what type of damage it will have. You can come up with it yourself. The point is only to give players the opportunity to use spells with visual effects of plants (roots, vines, flowers, mushrooms).
3. The grimoire is a familiar. Depending on the chosen type of attack, there will be different ones:
fire - fire atronach
ice - ice atronach
lightning - is a small version of the thunderstorm atronach (because sorc already has atronach in the form of an ultimate)
plants - spriggan
Poison - voroplasm?
physical damage - live armor
magic damage - ... Beholder, maybe.
4. The grimoire is a ray. Everything is clear here, an analogue of the arcanist's ray, but with customizable damage types. the only thing is, it should still be different. For example, it is not so long-range and long. Or its activation will require clamping the mouse (similar to the ultimate in sorc).
That's all for now, but in fact, there are still a lot of grimoires to think about. but it doesn't make sense to paint each one. Instead, I want to hear what you think about it, as well as what you would like from this amazing system.
UPD: I also thought that, in addition to the type of attack - plants, it would be nice to see water and earth magic. (You can give physical damage to the earth, it's just for visual aesthetics, and magic damage to water, although it would be nice to come up with something original for them). And also, I suggest that new grimoires (when they appear) can be obtained by buying not the grimoire itself, but, for example, its maps, which contain an image of the dungeon in which this grimoire is located. It would be nice if, in order to get a grimoire, you had to solve some kind of puzzle (for example, as in the quests of scribing, with these lenses and signs). Of course, it won't be as great as it was originally supposed to be (using charcoal on parchment to draw symbols that you find in dungeons), but nevertheless, as for me, it will be many times more interesting than a banal purchase. Go on an adventure to get a new spell, or just buy it. As for me, the choice is obvious.