Arcanists and their spells

[Nahara]

The books are indeed magical, as are the ink. Two texts from the Relic Reborn quest for the Omnilex and the Veil of Wiyu stand out:

Turns out the patterns on the cover are meant to improve the flow of aether from the wielder's hands. An' I'd thought 'em merely decorations. Ye learn summat new every day, eh?

I thought that the studs what adorn it were only good for holdin' the bloody thing together. But it turns out they're meant to channel the wielder's aether as well. Ye learn summat new every day, eh?

So we know that, at least in the case of the Omnilex and the Veil that the bindings of the books are designed in a way to better channel aether. Now, onto some text about the ink:

Ink fortified with X sand to improve aetherial conductivity.

The X is merely a placeholder for the various types of sand usable in the ink's creation, be it copper, silver, gold, rose gold, or whatever the Superior Enchanted Ink is made of that makes it better than the rest. You can think of it like the conductive circuits on a motherboard (all those copper lines); these lines can be drawn with a pen, so it's stands to reason the enchanted ink used to make arcanima grimories is similar in function, but works with aether instead of electricity.

[EDIT]
So if you really wanted to think it all through: The arcanist opens his grimorie to the page containing all the information necessary about the spell he wishes to cast, which takes the form of arcane geometries. The arcanist feeds aether into the geometries, which shape the aether into the desired form, which is then released onto your target as the finished spell. More advanced and/or personalized grimories can contain additional aetherial conductors as "decoration" on the binding to improve performance.

And thinking on it a bit more as I write this, the grimories are essentially computers for magic. Aether is to electricity, as the conductive ink is to the motherboard, as the additional conductors on the binding are to more RAM or an additional CPU.