This has specific rules for Wizards and Sorcerers. Does this the Arcanist does not get to play at all? Or will they act as one or the other for the purposes of the spell?
Yeah, I am not sure the language for the Arcanist is clear enough on this.
Unless I somehow missed it (possible even though I read it 3 times) there's no line that says anything that affects a Sorcerer's Spells Per Day can affect an Arcanist's Spells Per Day the same way.
Actually, very oddly, the "Spell Slot" terminology used with spontaneous casters isn't actually part of their description.
Obviously the intent is clear because we are familiar with the system., but the language could be a lot better.