Claws are curved appendages, sharpened to a point, that grow on the ends of the limbs of many animals. Typically Claws are used in the animal kingdom to grip surfaces and attack prey. Within the Legacy of Kain series, claws are implied to be a natural development of Vampires, which provide them with a basic weapon when unarmed;[BO2-C1] as such Claws are featured as a 'weapon' in Soul Reaver, Soul Reaver 2 andBlood Omen 2.
Claws were first able to be utilized as a weapon in Legacy of Kain: Soul Reaver (the first game in the series to allow the protagonist to be 'unarmed'). Raziel was able to extensively use his claws against enemies in Combat (see also: Combat (SR1)), where claws were faster than other weapons, but lacked much of the power. Raziel's claws, whilst allowing Raziel to perform several combos and effectively 'stun' a Vampire, were not powerful enough to finish them outright - instead Raziel had to take advantage of the surrounding environment to kill Vampires (using one of the 'finishing moves'), or alternatively impale the vampire using a Spear or other weapons. Raziel's claws were insufficient to permanently cleave and impale a vampire in themselves[SR1].
Claws returned inSoul Reaver 2, once again utilised as Raziel's default weapon whilst unarmed. Like their appearance in Soul Reaver, they were the quickest but also the weakest of the weapons at Raziel's disposal. Raziel could use claws extensively in combat against enemies (see also: Combat (SR2)) if he was not armed with any of the more powerful weapons. Unlike their use in Soul Reaver, claws were now powerful enough to penetrate and 'impale' an enemy (as he mostly fights humans, rather than vampires) enabling Raziel to execute a 'fatal blow' when the enemy was stunned, by ripping out their heart (possibly a nod to the fate of Janos Audron later in the story)[SR2].
Claws are only used as a weapon in games which allow the protagonist to drop, break or otherwise lose their weapons; in both Blood Omen[BO1] and Defiance[DEF], the protagonist cannot lose their weapons.
Though claws are generally mentioned in a combat/weapon context, they are likely to be involved in the Scale Walls ability demonstrated by Raziel throughout the Soul Reaver arc and Kain in Defiance.