Eureka is an optional dungeon, but it has all of the most powerful equipment in the game. It's entrance is in the Crystal Tower.
Eureka
Tip: if you are exhausted from fighting bosses (run out of HP/MP) and needs to refill, you can go straight to B8 because it has wellspring that can restore HP/MP and revive KO'd allies.
Note: Ribbon is probably one of the best armor you can get right now, it provides immunity to all status ailments.
Each weapon is guarded by a boss, you'll need to be strong enough to face them, so I suggest you farm a little bit, especially your HP (around 3000HP is ideal for this dungeon).
Boss: Amon (Moonring Blade)
This boss is a stronger version of Hein. Make sure that you have Libra (White Mage), otherwise, you can change to Scholar to study his weakness.
Boss: Kunoichi (Masamune)
Her main damage comes from Aeroga which is a single target skill. As long as you can keep up with healing/reviving, nothing to worry about.
Boss: General (Excalibur)
This boss can use Death which can instantly kill one of allies. Other than that, he doesn't deal any significant damages.
Boss: Scylla (Elder Staff)
It's stronger than other bosses because it can use highest level magic such as Flare and Holy to a single target which deal a great damage, possibly KO. Make sure to always keep your allies in full HP.
Boss: Guardian (Ragnarok)
He mainly uses Quake that deal high AOE damage and normal attack. One Curaga should bring everyone back to full health.
Chests (19):
- Fuma Garb
- Chocobo's Wrath (x2)
- White Musk (x3)
- Elixir (x4)
- Phoenix Down (x3)
- Ribbon
- Shuriken (x4)
- Omnirod
Items (5):
- Moonring Blade (boss: Amon)
- Masamune (boss: Kunoichi)
- Excalibur (boss: General)
- Elder Staff (boss: Scylla)
- Ragnarok (boss: Guardian)