@Asura I'm sure you could convince some Tech-priests to create a weapon along those lines for her as a post-mission reward. Or, just get a chainfist built to human scale; that already has both a chainsword and a power field attached to it, and I believe it comes with a storm bolter attached to the wrist too. Maximised Melee Murder Mode, Activate.
My original plan was to have her getting Abbadon'd in her early days (read; lost her arms) only to have them replaced by bionic limbs because Sororitas rarely know when to quit. To capitalize on the advantages of those metal limbs, I was gonna have her swing around an Eviscerator like some kind of Techno-Nun Barbarian.
Nothing quite says "vanguard" like chopping into a tank with as fuck off huge chain sword.