I think these two segments really sum up the point being made here:
Vahn Kyonuske
Viper's attack would be absorbed, and then re-distrubited right back at him, nearly tenfold as Vahn added his own energy to it as well the destructive energy he had just refined and harnessed due to Ymir's energy; creating a 'Dark Void'.
Basicaly Viper's attack would be reflected back on him in a reversely negative manner [...] with the same property as the reality distorting sphere;
the result would be a total nullifaction and cancellation of everything that made up Viper once they stabbed into his body, specifically penetrating each one of his innumerable 'centers'.
To put it bluntly, power exists in two two different types. There's power that it
gives off, and power that it
takes away. If these two powers are thrown into each other,
they should cancel each other out.
The attack in question... specifically saying: "I throw back what you just threw at me, only more AWESOME."
The intent seeming to be that if it connects the 'negative power' should cancel out whatever 'deep, inexhaustable reserves of powr' Viper has and leave the two of them in the classic end-of-a-climactic-anime-battle fistfight as they stumble around barely able to stand after running out of uberjuice.
Jans Viper
the first one pierced his thickly armored jacket like it wasn't there. Viper's insane reflexes were the only thing that stopped that first shard from being a direct hit, missing the "center" by the barest of millimeters.
The spears strike a boundary within Viper. Something vast and unimagiably powerful. And yet, it is clear that this indomidable aegis isn't a boon on Viper. It is a Seal of unrivaled strength, something that you can tell from the most simple of contacts
would be completely and utterly impossible for Viper to break. A Seal on his massive power.
In this quote we see a clear declaration of taking the hit.
Then we have this thing. This thing that Viper specifically describes as 'of unrivaled strength' and would be, without a doubt 'impossible for Viper to break'. Now, seeing as how it's Viper's returned attack that is trying to break down this door, you'd think that it would be completely and utterly impossible for that to break it.
However, there's the whole "returned 10x more" thing going on, and ten times is a lot of times. That, added to the 'negative polarity' thing that's supposedly happening which (should) cancel out Viper's powers (meaning that if Viper's powers are responsible for, and not just contained by, this barrier, then the attack should pass through it like butter).
Now... I can see this happening in one of two ways:
1. Viper has taken the hit of the power-negation, which results in (a vast majority of) power-negation. Though his little 'resevoir of power' is untouched because of the 'unrivaled strength' of this
WALL, so what we end up with is Viper being drained of all power on-hand and he'd have to siphon more out of his little reserve to continue the fight. That is
if he survives getting hit by a 10x uberblast that apparently has the possibility of breaking through a barrier that is so strong it "would be completely and utterly impossible for Viper to break".
Maybe he can't touch the black box but the airplane certainly isn't going to be happy with the crash.
2. Viper has taken the hit of the power-negation, which is strong enough to crack open Pandora's Box. However, if your poisoned knife manages to stick someone through their armor, that doesn't mean the poison isn't still there. Sure, the walls would come crashing down, but if the attack was strong enough to break that barrier, then obviously it's stronger than whatever was inside of the barrier trying to get out - and negates appropriately. As intended, both fighters would be left with nothing.
Oh, and... see above for the whole '10x uberblast' scenario, because apparently it would be more
bitchin' than anything Viper could possibly conjure (and subsequently, defend against).
As far as Omi's rundown of it is concerned, I think it'd actually go more like this:
Vahn: *Whips out the anti-mutant serum from X3 on Viper.*
Viper: *Flexes like Superman does whenever a gun is pointed at him.* Go ahead. By removing all my powers you'll take away the restraits on my powers.
Vahn: ...
Viper: It makes sense!
Vahn: *Pulls the trigger.*