Quote Originally Posted by Lithera View Post
Was it a SMN that got it? I noticed in a Brayflox run that SMN and I imagine SCH can remove their soul crystals in instance because I came in at Eft boss and the SMNs had downgraded to ARN to Topaz tank. After the boss they switched back and popped Ifrits. Can ARNs remove SMN crystal and put on SCH?
They cannot remove the crystal. Summoners do not lose access to the carbuncles until they do a quest for their egis. At level 35 they get a quest to replace the topaz carbuncle with Titan egi, and at level 45 they get a quest to replace the emerald carbuncle with Garuda egi.

As for the level 50 books, they are all either SCH only or ACN/SMN only. There are no end game books equippable by both scholar and summoner.