HeavyWeapon is a type of Melee Weapons in State of Decay. Weapons of this type all have a long handle and are heavy at one end.
Heavy weapon swings are quite slow, and have a significant delay between attacks. Thus, it is possible for the users to get attacked by zombies during this delay if the players don't position themselves carefully. On the other hand, a single swing can hit or even knock down multiple zombies, so heavy weapons are highly effective when dealing with large numbers of undead.
Using normal attacks with heavy weapons on a zombie lying down typically results in a downward blow that instantly kills it. This is also the case with AI-controlled characters wielding heavy weapons, making them very effective at finishing off zombies knocked down by the player.
Since the Powerhouse skill provides significant advantages when using heavy weapons (reduced Stamina penalty, faster swings), it is recommended that the player only give heavy weapons to characters with this skill.