Question: Can I take a single level of Arcanist or Exploiter Wizard, pick up Arcane Weapon, and then go into another class while retaining the Arcane Weapon level scaling?
Relevant text from AoN:
Arcane Weapon (Su) (Advanced Class Guide pg. 9): As a standard action, the arcanist can expend 1 point from her arcane reservoir to enhance her weapon. The weapon is treated as magic for the purposes of overcoming damage reduction. At 5th level, the weapon gains a +1 enhancement bonus, which increases by 1 for every 4 levels beyond 5th (to a maximum of +4 at 17th level).
Reasoning: Most (not all) other Exploits specifically call out Arcanist level scaling for their effects. Compare Flame Arc (deals +1d6 for every 2 levels) to Force Strike (1d4 damage and +1 damage per Arcanist level).