For all intents and purposes? Rei's Kekkai Genkai was COOL AS FUCK!
He had the ability to manipulate the mass and volume of an object.
Or, if you're stupid.
He can manipulate things with his mind, while also adjusting their weight. HE HAD A COOLER VERSION OF TELEKINESIS!!
The real limitation to it was the amount of chakra is used to keep it up, and the strength of his mind, which as a full-grown adult who had spent many, many hard hours studying to be a doctor, was already very powerful. Not including his evolutions and natural talent for multitasking.
He also got two other releases, Lightning and Wind, BUT TELEKINESIS!
More would definitely be explored in the future, in fact, he already has some 'Special' moves planned, shit that would change the very tide of the battle.
But, to talk about Rei's evolution.
The biggest thing is how much better his body is, quality-wise. Not only does his body process things better, such as fighting poisons, fighting disease, and many other small things even things such as filtering oxygen.
But it also takes a quality leap in speed, strength, healing, and overall durability, if Rei had to put a term to it, or a measurement, he was pretty sure that unless someone could leave a fist print in a sturdy tree, they wouldn't even be able to harm Rei, which yes in a world full of people that can pierce entire mountains, split lightning, and swim in lava if they wanted, that may not seem much. But people need to understand that is on top of his already chakra-enhanced physique.
He could hit harder, run faster, even think faster than the average of everyone on the planet. On top of his already genius-like skill and a sharp mind, it only made him even better, and even then if Rei can't reach the 'Pinnacle.' of evolution? What's to say his children don't come out with already pre-evolved genes, and can take it further faster because they start further down the evolutionary path?
The biggest change that came with this evolution is his ability to 'Sense' things around him, his senses had been cranked up to eleven, and through just sound, touch, hell even taste, he could locate someone quickly, his sight and sniffer could pick up a lot more things, and into a deeper sense than others. Yeah, he could smell someone's food, but he could also further take it and get a smell of what might else be in it. Maybe not useful, but in a place full of perfume, if he focused he would be able to single out one he knew better.
After some tests, he could tell his eyes were as good as an Uchiha with only one tomoe open, it wasn't a huge increase, but it was definitely better for his already great eyesight. How he tested it? Well, he watched the speed and reaction speed, mainly the eyes of their reactions of an Uchiha going through training and testing it himself, was he exact? He couldn't be sure, but it was a good thing to at least compare to.
His nose, while good, was nowhere as good as an Inuzuka, but in a way, it was better since he could focus on certain scents, and not simply being good at smelling. Only their dogs could do as Rei did, and his nose was nowhere as good as one of their dogs yet.
With all that aside, his chakra had seen a massive improvement, in quality and quantity, apparently the further you would go in evolution, the further... 'Raw' as Rei described it your chakra would become, more violent when simply released, the only reason Rei actually had such a violent reaction when he activated his Chakra was due to not only his evolution but his own meditation and attempts to better his chakra.
His chakra was 'Refined' even despite its rather wild appearance. Apparently, when viewed by a Byakugan, his chakra simply became a lot more 'Active', moving faster and more fluidly through his channels, and the core where his chakra was stored spun much faster when compared to others.
Rei's personal world was actually full of chakra now, purely because this increase apparently also affected his world, as his evolution happened, the time shift also increased, and things operated much more smoothly.
He was actually able to stock a multitude of herbs, plants, and other just plant life that would vastly help him to have a ready stalk for, the fairy that looked after his garden had actually become slightly bigger, now standing about 8 inches, it still looked to bright to see, but now Rei could at least see a form, and despite the voice having been female, he now knew that the fairy also had a more female appearance, even if it was a rough outline.
Rei had also introduced wildlife, simple things such as bugs, worms, and insects into his world which explosively began to increase just how large his world was as they were placed around to grow their own ecosystem, Rei even introduced a few types of fish he caught with got him a pretty decent sized lake, but since he hadn't got any fish fro the sea, he didn't have an ocean.
He also, had one mine, and it was a chakra metal mine, sounds pretty cool right? Already have such an expensive metal going, it was.
However due to the 'Rarity' and strength of the metal, the mine took a VERY LONG time to produce ore, even in the year since its introduction, Rei only had enough Ore to smith into a small tanto at best, which could also be seen as pretty broken, even just a tanto made of chakra conductive metal while also being incredibly strong meant that in each year he could make a new tanto.
Which, the weapon itself was deadly if used properly, but due to his chakra conductivity? In the hands of someone with wind chakra, lightning chakra, hell even water, it could be a terrifying tool in a ninja's arsenal.
IT was actually around this time Rei began to take an interest in smithing, he realized that he very well much planned to max all available 'Classes.' in this life, it actually reminded him of a friend he had in his past life who was considered the 'Jack of all trades.' in their group.
Rei took to Smithing with gusto! It was good to have something to help distract him from constant training while relaxing his mind, having an outlet from it all showed a small improvement in his mood.
(Get ya selfs a hobby. Mines writing, and no gaming is not a hobby. Not to me at least, it is fun, yes, I understand. But something productive, reading, writing, drawing, playing cards, magic tricks, something like that. It will help you in times you least expect it to.)
(Pa-treon.)