For farming arcantus, I recommend taking a fast air with weapons with a decent ammo supply, and a Sniping Unit. Drop the sniping unit in one area of the map where it'll be able to reach a large portion of anything that spawns, and stand in the opposite corner and farm there. Since the bit will kill anything in about 50-70% of the map, it forces the rest of the spawns to pile up in one area, where you can kill them en masse. If you want to, you can hold tab and watch what your bit kills, then see if any items drop, but from personal experience I'm pretty sure it's faster to just farm independently and let it kill things.
For UC, run all ten arcantus treasure routes once. That should take about 1~2 hours and turn out ~46,700 UC. After that, 3* frac and haku are the best bets; Frac drops more UC, but Haku's easier to kill quickly and since drops scale with time, if you can kill 3* in ~10 minutes (combination dagger's the only weapon strong enough) you can get ~1700 UC per run.
Also, I'll let you in on a little secret: tickets won't expire in the middle of a quest. If you have one minute left on a ticket and enter arcantus, you can farm every area for 9:30, and as long as you don't go back to the ground area the ticket'll work the whole way through.
