Tactics and strategy in Heroes of Might and Magic V.

Skilled Attack grants +15% melee damage. Skilled Defense reduces damage dealt to troops by 30%. Therefore, the advantage lies with the defender. Especially if the attacker's "attack" stat isn't exceptionally high.

I was also surprised by the attack's disadvantage. However, the attacker can benefit from luck and various special abilities of units. And Warlocks also have elemental chains. Therefore, the advantage of defense is not that great. If it exists at all. If the bonuses were the same, the attack skill would definitely be stronger. But as it is, it's hard to say. Each race needs to be analyzed to determine who benefits more from attack and who benefits more from defense.