Nocturne

Oersted induced 12 gauge S assault rifle
 

Discharges by having a magnetic flux barrel induce and accelerate spiritual energy.  The variable energy shell can be fired as multiple low-energy shots or as a single high-energy shot.

Although its original model name was serpent, it is said that the soldiers, seeing dying Phantoms writhe as if they were dancing in a ballroom, maliciously began to call it nocturne.
 

Notes: My favorite gun.  It's an energy weapon, seems all around easy to use, and it uses magnetism.