First of all, welcome to Souls Adrift, it's nice to see you again Xan and despite some of the below I--and I'm sure the others--would be glad to have ya ^_^

Anywho, on to the review and all that jazz.

[quote=@Xan the G]【Rekuzan Xero - X-0】[/quote]
Alrighty. So, I'll admit I have not yet read history/personality (the bio section) since I wanted to see what the zanpakuto looked like first (since that is typically what I need to review more than anything else). I'll take a look at Xero's "Personal Info," once we figure this out. So, without further ado, the zanpakuto review. Bear with me.

[quote=Shikai Ability]Ki-Manipulation. Légion has the ability to disrupt reiryuku like a physical sword can disrupt a physical body, making power leak like blood or Ki-skills malfunction like broken/injured limbs.[/quote]
So this is essentially fine and could result in some interesting effects. The problem comes in the area below. Aka, techniques.

[quote][u][i]Iemo-pi:[/i][/u] Xero will launch a spirit wave attack. If it hits a being with spiritual energy, their next use of spiritual energy will backfire. If it hits a spiritual being, the next reiryoku attack from their bodies or skill will either hurt them if it's intended to attack someone else or hamper them if it was supposed to support them by the same extent they expected it to work for them. If it hits a zanpakuto or other 'item' of spiritual energy, then the next reiryoku attack using or channelling through that item will backfire in the same way.[/quote]
So, I'm fine with the attack being able to hinder or somewhat disrupt someone's ability to access or control their reiryoku. However, what is not okay is the fact that it can essentially cause any attack/ability to "backfire," somehow. This is largely problematic for several reasons.

1.) Mechanically, that...doesn't always work. Some abilities manifest reiryoku and then allow the individual to control that. Causing something like that to "backfire," doesn't...really make any sense. So this wouldn't work on some abilities, for starters.

2.) It's...kind of over powered to be completely straightforwards and honest with you. Additionally, it doesn't really stay with the theme of your ability that you set in the primary description (that being the disruption/manipulation of reiryoku(ki) as if you were causing damage to it in a manner similar to damage caused by a physical weapon to someone's body.

So I'm going to say no to this technique. You can make something that weakens an ability or briefly disrupts their ability to use reiryoku-based abilities, but causing them to backfire or suddenly inconvenience them rather than help them is a no-go.

[quote][i][u]Seishin Shifuto:[/u][/i] Xero will stab the target in the heart in a passing lunge. The poke distorts what the mind feels as pain and what the 'heart' feels as fatigue. In the mind, the user will register lost reiryoku as if it were physical pain. The amount of pain they feel will depend on how empty (as a percentage of their total when full) they are of reiryoku. Additionally, the moment this skill is successfully used, the target will be 'caught up' by this phantom pain for the lost percentage of reiryoku in a single instant, similar to feeling all the strikes from an actual fight all at once. That moment can cause the target to flinch as well as raise hesitation as they use their spiritual energy, since each use of reiryoku from then on will make them feel pain. While this skill is in effect, it is possible for the target to pass out or faint from the phantom pain of energy loss without actually being hurt.[/quote]
So...no. This doesn't fit with the theme of your ability and it is [i]massively[/i] overpowered. It makes any use of any energy at all painful to some degree. I should remind you that reiryoku is a character's equivalent of [i]stamina[/i] meaning, living and moving around would also use it up somewhat. That coupled with any zanpakuto ability that uses reiryoku (aka literally every single one of them) and any ability that uses reiryoku (kido for example...and also anything at all that could possibly require energy) makes this completely unreasonable.

I'm sorry if that comes off as harsh. I'm just being real with you since I think anyone deserves that, you know?

[quote][i][u]Kiai-katta:[/u][/i] Xero makes a cut able to cut into reiryoku-based attacks as if they were tangible objects. Whether elements, waves or even vibrations, Xero can physically cut them or stop them with his zanpakuto. If he uses the back or flat of his blade, he can parry or deflect them rather than cut them.[/quote]

Now this is better, with the only part I have a problem with being the deflection. He's going to need considerable reiatsu and/or physical strength to be able to deflect attacks like that...and that's without considering the effects of any given reiryoku-based attacks. So you may keep his ability to cut reiryoku-based attacks with greater ease than others might, but he can't deflect them unless it makes sense (his reiatsu/physical strength stats would need to be around the same level as the other person's reiatsu stats or higher although I may change this after some deeper thought).

So yeah, those first two techniques are largely a no-go, and part of the third is a no. I would suggest you make a PM with [@Ganryu], [@Terminal], and myself to work on some edits and alternatives for the direction you could take the zanpakuto. Once we/you work that out, then I'll take a look at everything else and see if there's anything that needs alteration.