This boss fight is not nearly as difficult as its BNW counterpart, despite the LLG restriction. In fact, this is probably the easiest challenge that I've fought vanilla Atma Weapon in thus far. Even in a fairly standard LLNMG he's harder than in this playthrough. Getting as much damage off as possible is crucial to avoid a party wipe from Blaze, and although I may be blindfolded, this is the first time I've ever had access to the full toolset to take this guy down.
In an LLNMG (natural Magic), I don't have easy access to Float, I have less attackers, and the lack of Slow greatly increases the number of turns that he gets (sure I could apply it with Gau, if I were willing to awkwardly kill off and revive him). Unlike in LLNSNI (no specials, no Items), I have Aspik for Gau, Morph to increase Fire 2's power more, reviving is plentiful from Phoenix Downs, and since I can use Tinctures, Rasp (which can bring me down to 0MP, meaning I can't Osmose) doesn't cripple anybody. And unlike the LLNEG, I can use Earrings to boost my damage, and Reflect Rings help me survive his other attacks so that I don't waste time dealing with those.
When all's said and done, only being blindfolded isn't looking too bad at all! XD