Short blade

Short blades were short bladed weapons that traded power and reach for a faster swing rate.

12th century
Altaïr Ibn-La'Ahad's short blade was returned to him after he had reached the third rank. Like the sword, his skill with the short blade increased as he climbed up the ranks.

The first short blade he obtained had a wooden handle, though he received an all metal variation at a later rank. In both instances, he carried the short blade in a sheath strapped across his back, with the handle facing down.

In battle, he wielded the short blade with an, and often used it in conjunction with throwing knives.

Renaissance
In a similar fashion to Altaïr, Ezio Auditore was equipped with both a medium weapon and a short blade, though they were sheathed together at his side. He could purchase various types of short blades from blacksmiths, each with unique speed, damage and deflection properties.

In battle, he would wield the short blade much as Altaïr did, utilizing the same icepick grip, though he did not learn to use it alongside throwing knives until he became a Master Assassin.

Several of his allies, such as thieves and courtesans, also used short blades in battle. Certain guards and assassination targets, such as agiles and Rodrigo Borgia, made use of short blades as well. However, none of these held their weapons in an icepick grip.

Combat
Short blade strike more quickly than medium weapons, which makes them ideal for dispatching large numbers of low-ranked enemies. However, as an enemy's rank increases, the short blade's effectiveness diminishes, due to the higher quality armor they use.

For Altaïr, the special, close-ranged attack of most short blades can only be performed from behind, slitting an enemy's throat, or stabbing them in the shoulder or the back, which will always result in an instant kill.

When used with the short blade, Altaïr can throw a single throwing knife mid-combat. Similarly, Ezio can dual-wield the short blade with throwing knives, and can throw multiple throwing knives at once.

Trivia

 * In Assassin's Creed, Altaïr is the only person to use a short blade other than Malik and his brother until Malik loses his arm and when his brother dies. All other NPCs use long blades.
 * In Assassin's Creed: Brotherhood, once all throwing knives have been used up, the special attack of the short blade is switched to that of the fists, in which Ezio throws sand to momentarily blind and incapacitate his target.
 * In the blacksmith stores in Brotherhood, the Notched Cinquedea has the store image of the Channeled Cinquedea, and vice versa.
 * Unlike in Assassin's Creed II, in Brotherhood, the Channeled Cinquedea is a weapon that cannot be purchased, and can only be taken from a guard.
 * Only very few individuals throughout the series hold the short blade with an icepick grip. These include Altaïr Ibn-La'Ahad, Tamir, Ezio Auditore, Francesco de' Pazzi, Bernardo Baroncelli, and Claudia Auditore.
 * An unusable Notched Cinquedea can be seen stuck in the table in Ezio's room at the Villa Auditore in Monteriggioni.
 * In every Assassin's Creed game to feature the short blade as a usable weapon, there is a kill animation that Altaïr and Ezio possesses where the blade is not used at all. It involves breaking an enemy's leg with a kick, and then hooking their free arm around the enemy's head and snapping their neck.
 * In Assassin's Creed III, presumably because the short blade and the tomahawk use the same slot, Connor can perform stunts such as sliding along a rope with the short blade.