An anecdote, for what it’s worth: I’ve mained and raided almost exclusively with BLM since 2nd coil. I consider myself a good black mage - not great enough to warp a party, but generally an asset.

SMN and BLM are broken. I shouldn’t be able to practice a SMN opener 20-30 times on a dummy on Thursday and Friday and then equal or beat my top BLM parses on Sunday.

How do you fix it? Potency buffs are a given, but there needs to be more.

I like the idea of having a BLM-only utility ability, like Apoc used to be.

I want to be able to provide something unique to the party that noone else can: RDM offers unmatched chain raises which is amazing in progression. SMN offers damage debuffs for physical and magical sources. NIN offers Trick Attack and threat management. DRG offers piercing buffs and Battle Litany. MNK offers Mantra, MCH brings hypercharge, BRD brings Troubador. SAM brings a longer-lasting slashing debuff, which may not be unique but it's something. BLM brings... what?

Why not let a blizzard spell add magic vulnerability for 30 seconds or so, like the melee classes add for their respective damage types? Or, if you don’t want it to be pure damage, why not give a party-wide Mana Shift with half the Refresh cooldown? Why not give BLM a party-wide Apoc? Or a targetable Manaward? There needs to be something that only BLM can offer, and right now, that “something” doesn’t exist.