Or the worst case of the two combined: the Book of Darkness was a pre-Belkan era knowledge preservation and collection device. Its literally made to be an imperishable time capsule that will gather all knowledge it comes across, and maintain it in accessible format, complete with automatic indexing, self defense capabilities and re-instantiation in the event of complete physical annihilation.
Then the Warring Ages found it, hacked it into a superweapon, and promptly lost control of it.
An important element of Lost Logias is that they are generally stupidly durable, and in the cases where they CAN be destroyed, whatever serves as their reactor cores usually goes explosively. Doubly so for Al Hazard's relics, because Al Hazard fell to a total dimensional rupture, and well...only the most durable came out once reality finally equalized out.
Incidentally the Jewel Seed incident is an oddball case, because individual Jewel Seeds are not that destructive, since they are basically magical zero point energy generators hooked up to a brute force wish granting system, that fits it all in the size of a biscuit.
Remarkably stable for what they do really...except for the part where a mage who knows what they are doing and uses enough of them together could perform an extinction level event resulting in existence failure over multiple worlds.
Heck, what little detail we have points to their potentially being losttech from lost civilizations the Entities took along on their way.
