[Autumn]

In best case scenario? Hardly.

80 fire attack, mutated narcus for 100% scaled weapon attack and you have 60 scaled STR.

50% of 80 fire attack would be about 40 damage

Scaled Weapon ATK = (X% of [scaled stat(s)]*1.5) + (Power + Upgrades).

So that'd mean the Narcus would be 60*1.5 + 20(Not the exact number but an estimate), +6 from upgrade, equating to:
116 damage

So now we take the 40 from fire attack, add it to 116 and get 156, but it doesn't stop there, we also get +18 from explosive art.

174 unresistable fire magic damage

That doesn't seem very low to me.

So yeah, I think 50% fire ATK and 50% Scaled Weapon ATK is more than fair.