This is undoubtly one of the most useful tool in the Medic's equipment. With the ability to revive fallen teammates Medics can spell the fate of an assualt upon a flag or turn their crumbling defence into a formidiable wall.
As a medic you can level up the skill by using the training points obtained by levelng up you character.
Increasing the level of the skill will revive allies with more HP when used. The defibrilator will also fully replenish ammo excluding the Motion Sensor and Request Reinforcements that have certain cooldown periods. This means that if you are out of ammo and have a medic nearby, you can sacrifice HP for ammo.
Lvl 1: The ally is revived with 50% of his health
Lvl 2: The ally is revived with 80% of his health
Lvl 3: The ally is revived with 100% of his health
The defibrillator has an extra range boost compared to a combat knife. Thus, meaning the defibrillator is a tad bit overpowered.
You can use the defibrillator instead of your combat knife to kill enemies and get some LULZ.