Living
Unlike simpler forms of biotech, a living weapon is not just organic material—it’s actually a simple living organism. The core function of a living weapon is based on the same scientific principles as manufactured weapons, but come about as part of its natural development and body function. A living weapon can be affected by spells that target creatures, though it is mindless, incapable of independent action, and has no ability scores other than Constitution (which is always equal to its item level). It is subject to poisons and diseases, though it does not need to breath and is always protected as well as a creature with active environmental protection from armor. If it is forced to make a saving throw, its save bonus is always equal to its item level. If it suffers a condition that would normally cause it to take a penalty to attacks, damage, or save DCs, those penalties apply to any attack or effect created with it. Living weapons “eat” by absorbing part of the charges or fuel (or energy from some other form of ammunition) when fired. They do not sleep or breathe, cannot communicate in any way, are immune to pain effects due to their incredibly simple nervous systems, and are mindless. If damaged, a living weapon can regain Hit Points from effects that restore Hit Points to living creatures, such as a mystic cure spell, and it regains a number of Hit Points equal to its item level each day. You can use the Life Science or Medicine skill instead of Engineering to repair a living weapon.
Source
Armory pg. 29