Kienzan (気円斬), Krillin’s signature technique, is consistently depicted as an energy-based attack
capable of instantly cutting through its target, being described as able to cut through “
anything” and “
everything,” independent of the
user’s Battle Power. Unlike conventional energy attacks that rely on power differences, Kienzan functions through its extreme energy-slicing properties that ignore the target’s physical durability.
In its various appearances, Kienzan has been shown
to injure or
threaten characters statistically far superior to Krillin. This establishes that the effectiveness of the Kienzan is not determined by the user’s AP, but rather by the inherent cutting mechanism of the technique itself.
I can agree with this but parts of you're arguments aren't to solid in my opinion
In Cell’s case, the Kienzan should still be able to cut his body effectively, but Cell may have been able to endure it due to his extreme regeneration. In other words, Cell is not “immune” to the Kienzan; he is simply capable of recovering after being damaged. This would not be a failure of penetration, but rather a case of surviving post-injury. But then again, such assumptions may not be fully acceptable here,
especially since we also see the Kienzan shatter after passing through Cell’s neck. Considering that specific instance, it may not be unreasonable to assume that Cell possesses something that allowed him to withstand it.
You know Cell's regeneration abilities aren't that fast right?... We've seen when he's actually damaged and he never regenerated that fast, plus you can't even explain what just happened when you literally say
"it may not be unreasonable to assume that Cell possesses something that allowed him to withstand it.". So what is it? Did he regenerate or did he use "something" to withstand it?
I could just as well say when that spark/light effect happened on hit, that was the disc deflecting off to the side and give him resistance to durability negation (that specific form). Basically it's a terrible scene to try and justify, you'd be better off saying due to how it's depiction, it's unknown what just happened.
Meanwhile, Jiren’s case is different in context.
Jiren is explicitly shown reacting seriously to the Kienzan, attempting to read its movement and exploit a weakness or momentum point within the technique. This indicates that the attack is considered dangerous even by someone operating on a far higher power level. The absence of Jiren being cleanly bisected is not evidence that the Kienzan failed to ignore his durability; rather, it suggests that the attack did not strike him in an optimal manner. On the other hand, we have already seen
Goku destroy Krillin’s Kienzan with his energy blast, even though Kienzan
could penetrate Cell Max's energy attack, iwhich implies that he was also targeting a weak point of the disc similar to what Jiren did. Additionally, Kienzan does have weaknesses such as when it is launched from a great distance or used without proper strategy
which is why it is often portrayed as a surprise attack, either
relying on its attack speed or because the disc eventually slows down.
Jiren wasn't "serious", he reacted the same way he did when he charged at Goku and punched him. That standard look on his face. We've seen a serious Jiren and that wasn't it, especially trying to argue he reacted like that because it was "dangerous" to him is weird because he's shown blocking that Goku's punches despite we know that Goku at that time couldn't do much to him which is why he tried to ring out him!
Now, the argument on the way he struck them could be valid seeing as it looks like he doesn't punch it at an angle that would cut him (top and bottom). However arguing Jiren's reaction was serious as support that they were dangerous to him isn't good given that reaction isn't special.
As for Goku and Cell Max, it's blatantly obvious Goku blew his Ki blasts up on contact with the discs to destroy them, meanwhile Cell didn't. This is something shown in the verse a lot, several characters ki attacks detonate on contact while others push and blow up after.. Cell's is a good showing that it can cut through stuff but Goku isn't capable of being compared to Jiren because one was physical strikes that shattered them while the other was just detonation on the disc.
The most consistent interpretation is that Jiren did not “tank” the Kienzan through sheer durability, but instead read its timing and looked for openings to avoid it or to secure momentum. Within the context of the Tournament of Power, Jiren heavily relies on efficiency of movement, instant reactions, and battlefield control. Avoiding the Kienzan is far more rational than attempting to tank an energy slice that mechanically does not rely on Battle Power differences.
Logical but not based on comparison to Goku's method in my opinion.
Despite this, I think durability negation can be justified because of the statements, specifically the ones that say it has a "unique property". This phrasing sets it aside from other flowery language because its telling us it has some special mechanic and you can see it in the scans the OP, I'll explain.
Notice that against Frieza it cuts through his tail and keeps going and it cuts Nappa's cheek and keeps going. However,
look when it cuts the rock after Nappa avoids it and when Jiren
throws it at the rock and it cuts. It's clear that when it hits an object with a greater surface area, it severes the entire object in question despite not remotely covering the the entire are. This shows a unique property when it cuts so one can see that using the statements that it can cut through anything + it saying independent of battle power and has a unique property that displays more of itself when coming into contact with larger targets.
Overall I think it's got some valid justification and do agree with having durability negation but I don't know all the instances of the move being used so I can't say if my later interpretation (regarding the object size) or the statements provided are heavily contradicted. I'll try and keep tabs on the thread but you can put me down on agreeing for now.