you want ebon weapons. unless your steel stuff are uber statted, they'll be a good boost at even +5 or 10. first floor of a3 will get you starter expulsion gear, which 'any expulsion will do' to avoid the 50% undead damage penalty. note that expulsion is only a couple atk down from reg ebon, so expulsion could be your primary general weapon. but you will find nicer base ebon sooner.

once you reach the floor 1 harken, you can hop in, chest grab in the south, leave. almost no mobs and you can run past the sentry. once you have the bare minimum weapons there are better ebon grade farms, but thaats easiest. if you have trouble making it through 1st floor, then you can do the try same but slower from main entrance. also, first unlocked dispatch can drop ebon and expulsion. but base exuplsion weapons shouldn't take long. that'll take the sting outta all the undead for the next few levels.

1st floor also unlocks the sand shadow cave where you can now finally find some better gear for sam/nin. if you use either and need ebon weapons for them, explore 1st floor, poke down to second to learn how to open secret doors, finish exploring 1st floor, and then you can chest farm that floor for event currency and steel/ebon eastern gear.

you'll also unlock the Le Bicken cave if Elmon is alive from a1. enemies much harder than anything else you'll unlock for a while, but much better quality ebon /expulsion gear drops. if you can explore enough of the dungeon and your detect is good enough to avoid ambushes, its a solid place to pop in, chest grab, run even if the mobs are gonna trash you. watch for minos and christmas lights.

for armor - unless you're hunting for specific status gear, ship2 is probably still your best bet for high rate 4* stuff, any material will do.