HawkEye Xbow XH-II

The Xbow XHII is a weapon in Deus Ex: Human Revolution and Deus Ex: The Fall.

Background
The Xbow XHII is a light and foldable crossbow manufactured by Stasiuk Arms Inc. It has a 4 pulley system and specially shaped bow segment. This weapon uses Guillaume Tell Golden Arrows, which are polycarbonate, carbide-tipped, fin-stabilized bolts and are manufactured by Kaiga Ltd., a Russian weapon manufacturing company.

Characteristics
This powerful and compact crossbow allows its user to pin targets to walls. It's the perfect stealth weapon, removing threats with minimal disturbance. The crossbow can be equipped with an electronic sight that calculates the lead distance required to hit a moving target.

Bolts fired from this weapon can be retrieved after a kill around 30% of the time, otherwise they will break. (It should be noted that retrieving the bolts must be picked up as a normal object, not looted from a corpse.) The game can be saved right before picking up the bolts, thus making them always retrievable after a quickload or two.

It is also possible to perform multiple kills with one shot from the crossbow. If the player shoots the bolt from such an angle that multiple people are lined up (in the direction of the bolt's fly path), the bolt will hit the first, and the bolt tip will follow through (effectively carrying the ragdoll of the first victim) and will kill the others in the way. This works because unlike the other weapons (excluding the tranquilizer rifle), the crossbow bolt (when fired) is actually a physics prop, whereas guns are hitscan weapons. This hence means that it is theoretically possible to carry out more than 2 (for which number this has been confirmed) kills in one shot, at least until the bolt loses velocity or hits a environment obstruction. It should be noted that this will most likely not work later in the game as the enemies encountered later in the game, will not die from a body shot (especially on "Give Me Deus Ex" difficulty), and will only successfully kill all such hostiles if the bolt scores headshots on all of them in its flight path.

Locations:

If the player speaks to O'Malley on the first visit to Detroit, he will tell them that a crossbow (The murder weapon that killed an unnamed drug dealer) is hidden in the trash across from the Chiron Building. At the end of the quest, Jenny Alexander will ask for the murder weapon back. (The player can refuse but this will hurt their chances of winning the case.)
 * Can be retrieved from Jenny's body, after handing it over.
 * Bought from various blackmarket vendors.
 * Inside the porter building at Belltower Dock Yard.
 * Inside a storage room behind a level 4 panel, near the bot patrol, in Singapore / at Omega Ranch.

Behind the scenes

 * This weapon was probably inspired by the Twinbow II crossbow.
 * This weapon uses Guillaume Tell Golden Arrows, with an apple brand on the box. The bolt's brand name was likely inspired by the Swiss folk hero, William Tell, a legendary marksman who shot an apple placed on his son's head when challenged to do so in exchange for both their lives.