Spine Graft
The more Levis grows into its technology that's independant of the magic, or at least not as powered by the magic as it could be, the more the academics and creators of Levis develop biotechnology. This particular development comes from the Nocturne empire and is one of their greater scientific discoveries. The (human sized Nocturne) developed the device to help swim those of their kind that would be damaged in strong underwater currents and yet still need to move and swim in the sub-nautical environment.
Given the nature of Levis, one might be surprised to see that while invented by the Empire, the manufacturers and public face of the Spine Graft is the House of the Arcane. The House of Arcane at the time had a dignitary within the Nocturne Empire to discuss trade with their guild house. They were in the effort of building up their potential and clout, and when the discovery was shown to them, a quick copy of the plans were made and brought back to the surface.
It was here that the global community was given the choice - deal with the slightly-shunned from the largest power base on the continent, or travel under the sea to a land of foreigners and attempt surgery while trying to breathe underwater. It soon became obvious who the people would choose.
Mechanics & Inner Workings
The bio-graft itself mimics and enhances the neural pathways down the spine while also providing structural support for a damaged spinal column. The kelp that forms the base structure is grown in such a way it contains vacancies and the correct chemicals that promote actual nervous system growth into the kelp itself. Meanwhile the ahesive 'glue' keeps the kelp applied until it can grow into the flesh and begin to grow around the spine of the recipient. The kelp itself needs the spine to attach to, as that has the correct 'biostuff' and the kelp tends to grow fast enough that applying it to legs or arms will kill mobility. After enough growth has happened, a retarding agent is applied as an ointment to slow the growth enough that plant and person are confused enough to biologically think they are the same thing.
Advanced use:
While the Spine graft is amazing at reconstructive surgery, it also enables enhanced muscle growth over the shoulders and back with the greater than base skeletal support, and tends to encourage enhanced physical reflexes in the patient (whether the mental reflexes keep up is another standard). This has seen physical specimens that are not around the upcoming to begin experimentation with use of it as a body enhancer, though only time will tell if it takes off.
Glaring Flaws:
The kelp used in the spine graft has two glaring weaknesses. The first is that it is highly susceptible to Starlight Rot - while not entering a feeding cycle such as the photovoltaic cells, the kelp will still decay when exposed to the fungus, and while botanical necromancers might be able to stop the rot on a plant, the interaction with a humanoid body is not one they are willing to try. The second is that many forms of magic react in unexpected ways around the kelp, probably due to the nature of the magic that was used to enhance the original kelp into this biomedical kelp. Most notably, a concussive force spell when used close by will propel the graft wearer back - the strength of the push being cubically proportional to how close the spell and the wearer are.
This made my skin crawl. Bravo!