“One favor from each bank” is insufficiently specific. There are 5 banks with favor on them. But with this set of instructions I would assume you leave the favor on Arcane.
The spirit snare trade would ordinarily get you 2 favor (1+1), but Arcane only has one favor left on it, so it would only get you one. Better perhaps to save the supply and just use the Spirit Snare minor action?
Anyway, that may affect your whole turn, so I won’t make any assumptions.