Fighter HP: increase
Fighter DEF: increase
Fighter ATK: increase
Zephyr is definitely one of the more interesting heroes as his hero skill Counter Mirror causes counterattacks for 4 rounds whenever he or adjacent allies are hit. It’s quite frustrating in arena when its used against you, and can mean the difference between life and death.
He also has a heal over time like some of the other healers like Eve. He definitely feels like more of a defensive hero than an offensive one, even though he is a fighter himself.
He should be leveled to 131 to get all three troop skills unlocked.