Any tips on the Final Boss?

[Tainted Galaxia]

So as you saw in the video, what do I need to fix and how? I can go back to grinding since I didn't exactly saved after entering the small area where it prevents you from going back.

Part 1: https://streamable.com/dfl99
Part 2: https://streamable.com/mjx4o

[[サガ] Baz]

The configuration that i ever use for this battle is the next:
*Formation: Divine Wall
**Spells
-Missile Shield (Emperor & Healing Mage)
-Galactic Rift (Emperor, Offensive Mage and Healing Mage)
-Solad Wind (Emperor & Healing Mage)
-Sword Barrier (All Members)
-Revive (All Members except Healing Mage)
-Mist Cover (Healing Mage)
-Crimson Flare (Offensive Mage)
-Firewall (Offensive Mage)
-Life Water & Physic Water (Healing Mage)
**Skills
-Shattered Petals (Emperor and two soldiers)
-Yo-yo (Emperor and two soldiers)
-Avoid Hypnosis (All Members)
-Avoid Soulsteal (All Members)
-Flowing Slash (One or Two Soldiers)
-Blessing (Healing Mage with the Liberty Staff)
**Armor
-Black Gardiehl (Def. 42)
-Darkstone Ring, Intaglio Ring and Somon Ring
-Other
**Weapons
-The best swords & axes avaible.
-A lot of Quality Balms (I don't think this count as weapon but well...)
People usually recommend use the Rapid Stream formation or the Hasten Time formation, but for me, that made the battle harder.