The Pulsar Advanced Weapon Systems XM1 Neutron Pulse Pistol, affectionately nicknamed 'Celestia's Grace' by its developers, was left long-forgotten within its armored weapon case in a development lab at the heart of Buckston... until an Enclave Outcast with a penchant for experimental weaponry found it, that is.
The weapon itself is an improvement on current energy weapons technology, and uses an internal magazine to superheat slugs of metal into a plasma, projecting the bolts through a series of superconducting coils lining the twin barrels before they depart from the weapon at incredible velocity. More stable than conventional plasma weaponry with the speed and accuracy of laser weaponry, this state-of-the-art prototype successfully marries both ideas to create an even more lethal weapon.
"That's not how plasma is formed!"
Suspension of Disbelief, folks. It's a fic based on a fic that in turn is based on a theoretical merging of a series about a post-apocalyptic wasteland and pretty pastel ponies.
Celestia's Grace is the backup sidearm of Mach from my fic, FoE: Outlaw, which you can read here: [link]