Arcanist Archetype, Unlettered Arcanist
The Unlettered Arcanist has a few problems.
This character gains spells from the Witch spell list instead of the Wizard/Sorcerer spell list, and stores those spells in a familiar in place of a spell book.
HOWEVER, the archetype does not gain an Outsider patron as a Witch does. The Outsider is the source of the Witch's spells so they do not have spell books. Does the Unlettered Arcanist have the ability to learn spells from a Wizard/Sorcerer spell book? Or do they need to find a Witch to teach them new spells?
This seems a significant omission.