Amp

Overview

The Amp is a makeshift weapon designed and built by Zeke Dunbar for use as a bludgeon for his best friend, a powerful Conduit named Cole MacGrath. Essentially a double-pronged metal baton, Cole channels his electrical superpowers through the device, allowing him to deal devastating electrical strikes against his foes when he gets up close and personal, something like a supercharged cattle prod. The Amp is collapsible down to about half of its full length, and when he is not actively using it, Cole carries the Amp in a special strap on his backpack. Just like Cole's body and clothes, the Amp will change appearance to reflect his Karmic status: at first, the device is slightly dirty and rusty, but as he becomes more Heroic, it will lose the grime and rust and eventually shine bright, like it was made out of polished silver. If he becomes more Infamous instead, the Amp will become even more dirty and rusty, looking likely to give someone an infection just by touching it. 
 

Ultimate Fate (spoilers)

In the Good ending to inFamous 2, the Amp is recovered after Cole's death and embedded in the top of the memorial the people of New Marais build in his honour, serving as a shrine to the man who saved the world. In the Evil ending, the Amp slips out of Cole's grasp after the Blast, and he does not bother to recover it, abandoning it in the rubble as he leaves the city because it reminds him of the friend he killed.
 

Trivia

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  Several alternate skins are available for the Amp; none of them alter its abilities or strengths in any way, and are all purely visual. These include a samurai sword, a spiked "caveman club", and the signature cane used by Sly Cooper, the protagonist of the video game series of the same name. In addition, those who pre-ordered the Hero Edition of inFamous 2 received an exclusive skin that made the Amp appear to be made entirely out of gold.
• A life-sized replica of the Amp can be seen on Kevin Butler's desk during the inFamous 2-related "Ask Sony" commercial, though this prop was never made available as a piece of merchandise.
• inFamous 2 is the only game to focally feature the Amp. In the original inFamous, Cole merely attacked enemies with his hands and feet during melee combat, slightly enhanced with electricity, and in the downloadable game inFamous 2: Festival of Blood, although Cole starts the story with the Amp, he loses it after being attacked by the vampire followers of Bloody Mary. He then replaces it with the Stake, a makeshift weapon made out of a fragment of the lid of a coffin. It is unknown whether or not the Amp will appear in future instalments of the inFamous franchise.