Heavy weapon

Heavy weapons were weapons that relied on sheer force and power to inflict bone-breaking damage.

Strength
When swung with sufficient strength, the weapons were able to smash through attempts to parry with smaller weapons. Opponents caught under the full weight of the blow mostly collapsed or could even drop their weapons. Heavy weapons could only be countered by Long or other Heavy weapons (with the Hidden Blade being an exception, as it can counter any weapon; though the timing involved makes the maneuver more difficult and thus risky).

Defense
The Assassin Ezio Auditore could disarm his opponent with his fists. If he was equipped with the Hidden Gun or Poison Blade, Ezio would automatically counter with his Hidden Blade. Counters with these powerful weapons were always lethal to the target, but sometimes he would leave the weapon in the victim's body.

Smash Kill
Before the siege of Monteriggioni, Ezio acquired the Smash skill by Training, and he could use it whenever he had a Heavy weapon equipped. A smash took a long time to build up, during which he was vulnerable to interruption. But when a fully charged Smash connected, it broke through enemy defense to cause a large amount of damage and further effects. It was unparryable, and the victim would get disarmed, or may have had a long weapon broken.

When in Rome, the Smash skill was no longer available, and had been replaced by the ability to throw heavy weapons at enemies. This could be done to perform instant kills on enemies up to around ten meters away. Note that one would have to pick up the heavy weapon after throwing it, and if the user picked up a different weapon, their weapon would change to that, and one would have to go to a blacksmith to re-equip the heavy weapon (at no cost). This skill did not need to be learned, unlike the Smash skill.

Heavy Sheath
Ezio could purchase a heavy sheath from a Tailor shop after he had traveled to Rome. This allowed him to equip two-handed weapons as his primary weapon, so that he had a choice of 6 more weapons. If Ezio had a two-handed weapon as his primary weapon, however, he could not carry another primary one-handed melee weapon (e.g. Swords, Warhammers, etc.). If he dropped his heavy weapon, he could pick up a different one that he had not yet purchased and equip it, (you can re-equip one-handed weapons upon returning to the Tiber Island Hideout, as well as armor).

Assassin's Creed Revelations

 * Cappadocia only.

Trivia

 * Heavy Weapons can be re-obtained from bodies after they have been lodged in them through combat by simply picking up the body, which will cause the weapon to drop. This also happens when a long weapon has been lodged into bodies.
 * The maximum amount of combo hits is 3.
 * Players can disarm a weapon attack from Brutes in the first attempt, whereas it can take several attempts to disarm Elite or Leader Guards who are considerably less powerful damage-wise.
 * Heavy Weapons are the most common weapons used by the Mercenaries.
 * In Assassin's Creed: Brotherhood, Ezio has the ability to throw heavy and long weapons at his enemies. Heavy weapons will get stuck in the target's head while the long weapons will impale the target.
 * Taunting with the "Head" button will make it easier to disarm tougher guards such as Brutes or Papal Guards.
 * In Assassin's Creed II, brutes can be disarmed easily; however, in Brotherhood the brutes are very difficult to disarm, making the heavy weapons harder to obtain.
 * A heavy weapon cannot be used to knock a guard off his horse; a medium sword is needed for that. A heavy weapon (like medium weapons) can counter a guard on his horse and knock him off in Brotherhood.
 * Assassin Apprentices below the rank of Assassino can wield axes. While these weapons are described as axes in the loadout screen of the Apprentice, however, they can manifest themselves as heavy swords as well.
 * In Assassin's Creed: Brotherhood, although Ezio can no longer perform the Smash skill, enemies still can. They can not, however, perform the disarm move.
 * Occasionally, when a heavy weapon is thrown at a guard that is in mid-air, it will stay in his head and he will stand still. The guard will appear dead and won't attack Ezio. When the player removes the heavy weapon from the body, however, the weapon will fall to the ground and can be retrieved as usual.
 * In Assassin's Creed: Brotherhood, heavy weapons lack the ability to counter-attack other heavy weapon/long weapon users, except during an execution or counter-kill animation. Long weapons retain the ability to counter other long weapons/heavy weapons.
 * In Assassin's Creed: Revelations, heavy weapons can now be countered against with medium weapons.