Weakening Breath is not curable by Panacea
The 5th edition version of the Weakening Breath breath weapon is not labeled as a curse, disease, or poison. As such, it can’t be cured by Panacea, which says:
You remove all curses, diseases, and poisons affecting a creature that you touch with the transmuter’s stone.
In addition, spells like lesser restoration:
You touch a creature and can end either one disease or one condition afflicting it. The condition can be blinded, deafened, paralyzed, or poisoned.
…and greater restoration:
You imbue a creature you touch with positive energy to undo a debilitating effect. You can reduce the target’s exhaustion level by one, or end one of the following effects on the target:
- One effect that charmed or petrified the target
- One curse, including the target’s attunement to a cursed magic item
- Any reduction to one of the target’s ability scores
- One effect reducing the target’s hit point maximum
…which can remove most conditions between themselves, can’t remove it either.
This is a marked change from past editions, where the Weakening Breath was easier to handle.
The attack of a gold dragon can be a claw/claw/bite routine or one of two breath weapons — fire in a 9” x 3” cone, or chlorine gas in a 5” x 4” x 3” cloud.
Chlorine gas is just a poison that the neutralize poison spell could handle:
A gold dragon has two breath weapons: a cone of fire 90′ long, 5′ wide, at the dragon’s mouth, and 30′ wide at the end or a cloud of potent chlorine gas 50′ long, 40′ wide, and 30′ high.
Very little changes for the gold dragon in this edition, and the same spell helps here once more.
A gold dragon has two types of breath weapon, a cone of fire and a cone of weakening gas. Creatures within a cone of weakening gas must succeed on a Fortitude save or take 1 point of Strength damage per age category of the dragon.
We finally have the term “weakening”, but in this case it is ability damage (something that doesn’t exist in the same magnitude anymore). The move away from ability damage in 5e extended to the gold dragon’s breath weapon. Back in 3.x, though, it was more common, and both lesser restoration and restoration spells could help with the effects.
Close blast 5; +19 vs. Reflex; 2d8 + 7 fire damage, and the target is weakened (save ends). Miss: Half damage
In 4e, this recharge power combines both breath weapons, making the fire breath include the weakened condition. You can use First Aid to allow an ally to make a saving throw against the condition, but there may also be powers (though I couldn’t find one) that can end the effect immediately.
As you can see, past editions made the gold dragon’s alternate breath weapon easier to counteract at least to some extent, while 5th edition’s version must simply be waited out.