Lore of the wizard's grimoire

[Samugol]

Hi, 

 

I have been playing for a while now, and there is this one thing about grimoires that I cannot make much sense of. I was wondering if there is anyone who could shed some light on this. 

 

From reading some of the lore on wizards on official wiki, it seems that grimoires are special books, made from special materials that gather the residual soul energy from the area around the caster. Also the caster by himself cannot do much without a grimoire. This can be seen in the game, when you unequip the grimoire, the caster is unable to cast. 

I have been using Aloth as a companion and did not think much about it, until I started using Concelhaut's Parasitic Staff, which is a 1st level wizard spell that summons a nice quarterstaff.  

 

When you have a 2 handed weapon equipped (or sword and shield, or any two handed option for that matter) the grimoire disappears and yet, you are still able to cast spells. The animation is different though. It is the same as when you hold a grimoire, but this time only the funky light around your hand appears (as if the grimoire disappeared). There is a specific slot for a grimoire that only wizards have (much like equipment, not a weapon). Does this mean that a grimoire is just some kind of conduit, that you can have somewhere (anywhere) on your body and cast the spells with it? Or do you strictly have to hold it. In which case how do you cast with a 2 handed weapon. Is it a quality of life thing? Design choice? 

I am really curious. Any other info about lore of wizards/grimoires is welcome (such as what materials is it used from or who constructs it).  Thank you for any responses in advance.