I'm not sure if we're allowed character backstories here as well, so I'll just start with the saber pitch. NB: the concept art (and actually a chassis for the cram-fu; and also a lot of patience from me throwing ideas at him until one stuck - thank you!) was created/provided by @zharrhen. https://imgur.com/a/HdJp2TM
Concept:
Dual Matched Short-Hilted Shoto Sabers, one with a Jedi Blue blade, one with a deep Sith Red blade, The Jedi one would be heavily battle-damaged and barely functioning (likely with a damaged font), and the Sith one would be near pristine - likely polished and shiny.
Character Backstory:
The clone wars era. Unnamed Jedi. Scout mission deep in separatist territory.
The Jedi's team of troopers is ambushed, and after a huge explosion (the source of the damage on the Jedi saber), the Jedi is left behind during the retreat, presumed dead.
He is not dead...
He is found, tortured, and eventually turned by Dooku. He harnesses all of his pain, all of his anger, all of his bitterness and, most of all of, his deep betrayal at being left behind, and pours it into constructing a new saber, modeled on his now barely functional Jedi weapon. He keeps both weapons, as a memento of his past and his future, and vows revenge on those who abandoned him in his darkest hour.