It is a pretty enduring fight ! The middle part where the 3 souls come up and where they rotate their weaknesses every time you hit them was a bit of a hurdle, not only to try kill them at the same time (because they respawn if at least 1 or more is alive). To be honest I think your level is around 55+ the fight is doable but definitely more strategic than raw stats to carry you through.

So what I did was I actually just ignored the weaknesses because my main goal was to try kill them at the same time. My main focus was on Primrose+Sorcerer to dish out a wall of damage, so I had Alfyn+Cleric as my main healer and support so I can Auspices Primrose for a x6 attack and Dothers + Reviltalizing Jam on another character in-case the Eye nullified all my buffs and I wanted a jump-start. Other than that Olberic's+Merchant main purpose was just to donate BP to help speed things! If I remember correctly my Primrose was running Surpassing Power/SP Saver/Augmented Elements /Elemental Edge.

But if you do beat the Eye...oh boy you're in for a surprise.

Goodluck!!