got 2 atma relics. can i decided which one i want to upgrade when i hand in books?

[KoroushSensei]

or is it tied to the weapon i started books with?

[zonderbunny]

each weapon has different books (if I remember right, its been awhile and I'm old :P) So I think the book is tied to the weapon. That being said once you turn in the current book you may be able to get a book for the other weapon instead.

[KoroushSensei]

will i have to do all nine books again or just the ones i have not completed?

[zonderbunny]

You will need to do all nine books for every weapon you want to get to the next relic step.

[Daemius]

Whatever weapon you have equipped when you talk to the npc is the weapon you will receive a book for. You must complete or discard that book before you can get another book for that class or any other class. If you discard a book without completing it, all your progress is lost. If you switch to another atma and get different books any completed books you have for the other class will still be completed. Does that answer your question?