Fierce Breath grants Special cooldown charge +1 only when the foe initiates combat.
The Special cooldown charge +1 applies for both units' attacks.
A foe with Creator Sword will neutralize the "Special cooldown charge +X" granted by Fierce Breath.
If a foe initiates combat against a unit with Fierce Breath and the unit is inflicted with Special cooldown charge -1, such as from a foe's Guard Sword+ for example, the effects will stack and the cooldown will go down without penalty or bonus.
The stat increase that can be applied by Fierce Breath is considered a combat boost.