Any natural appendage can be considered a weapon itself. There is a simple beauty in the movement and lethality of melee combat. A character trained in the martial arts, or who happens to have an insanely large forearm, is never unarmed. Fists and fighting games have largely been associated with such weaponry, but Faith in Mirror's Edge can kick a man in the groin with startling accuracy and Mario's feet can be surprisingly deadly. I do not doubt the value of a simple swipe, there is something to say for the zombie hordes and the menace that is their shambling corpses. What most interests me however, is the blend of recognizable weapon traits with the natural characteristics of the combatants, which I categorize into three classes.
The first class of weapon-appendage is that which closely resembles a normal body part, but has the traits of more advanced weaponry. One could easily include a great deal of projectile hurling enemies in this category, but the more "technologically advanced" appendages are far more interesting. The tongue is a classic example of such an appendage. Left 4 Dead's 'Smoker' zombie has a sniper like tongue that lassos and drags in its victims. Similarly, the aptly named 'Licker' from the Resident Evil series can lash or pierce its prey with its abnormally long tongue. The 'Plasmid' wielding hand in Bioshock is another example of weapon appendage, able to hurl lightening or bee swarms at unsuspecting foes. The first class of weapon-appendage cleverly disguises the traits of classic weaponry into a compact frame while maintaining its combat utility. When wielded by an enemy, it can be equal parts shocking and disgusting.
At home in horror and the often attached to grotesque creatures, the class two weapon-appendage acts like and resembles a classic weapon such as a club, blade, or projectile. Such hideous creatures like Starcraft's 'Zerg' race exemplify this type of critter. With similar spear or sickle-like slicers jutting out of shoulders and torsos, the reanimated inhabitants of the USG Ishimura in Dead Space are particularly horrifying manifestations of the weapon-appendage combination. The idea of a creature born with such devastating and lethal weapons are naturally unsettling. What deity would breed such an abomination, let alone one who's sole purpose is to create carnage? These deadly limbs, frightening mockeries of man-made tools of war, are more suitable on enemies; thus, it is rare to see the class two weapon-appendage on a player controlled character. The closest avatar that could fit this category is Jackie Estacado of The Darkness.
Many of us are familiar with the class three weapon-appendage: a weapon in the place of a limb. The pirate hook falls into the category, as do the ridiculous prosthetic weapons in Army of Darkness and Planet Terror. Perhaps the origin of the class-three weapon appendage in videogames goes back to 1987 when two powerful franchises were created: Metroid and Mega Man. Though some images of Mega Man depict him wearing a wrist-mounted blaster, freeing the use of his hand, the common rendering is similar to Samus Aran's weapon-arm. Chronotrigger's Robo joins this team in 1995 with a rocket-propelled fist. Barrett of Final Fantasy VII, Baiken of Guilty Gear and Drachma of Skies of Arcadia can also be considered wielders of the class three weapon appendage. Unlike their progenitors, these characters' weapons replace permanently lost limbs, perhaps improving on their design.
I am writing this post for a couple of reasons. First, weapon-appendages are pretty awesome. That aside, the weapon-appendage is an interesting design choice. By incorporating weapons into character models, game designers create a unique being and weapon all at once. Looking at the list above, these characters are fundamentally associated with their weapons. The effect can be to shock and horrify the player, as is the case with Silent Hill's 'Pendulum', or humor the player with ludicrous weapons, such as Bayonetta's hair attacks.
A weapon-appendage can also free the design team of potential ammo and weapon modeling concerns. Bioshock's 'plasmids' are clever work-arounds to give the player a permanent weapon with all sorts of bizarre powers that has only one source of ammunition: a quick syringe to the forearm. Any class of weapon-appendage is an in-game manifestation of control. If the player controls the weapon-arm he/she feels empowered. If the enemy has a weapon-arm, the player feels more vulnerable. The weapon-appendage is a strategic and fun creative device worthy of praise, respect, and sometimes ridicule.