User blog comment:Thesupremejoyner98/Grimm that can cut through aura/@comment-9090085-20150114094931

No.

And I don't mean that your scenario is bad, in and of itself, but that I don't think it fits in RWBY; mostly because it ignores the purpose of Aura in my mind.

That purpose, as I see it, is two-fold: The first point of Aura is seen in a number of fights, like allowing Roman to come back swinging after getting slashed in the chest in Black and White; or Blake and Adam to blasted out a train car by a Big F-ing Laser in the Black Trailer without dieing; or just making Yang's fighting semblance appear OP instead of suicidal(could you imagine Yang getting hacked up and with broken bones in order to use it? Sure, it would work, but she'd have to go to hospital after every fight).
 * To make cool fight scenes where getting hit once doesn't mean that the fight is more-or-less over(you know, unlike in real life).
 * To allow people to lose fights and not die(similar to how Knightmare Frames in Code Geass have ejection seats).

The second point much more meaningful to me: in No Breaks alone we see the WF Grunts, Yang, Weiss, and Roman all come out of their fights unconscious instead of dead thanks to Aura; of course, this didn't prevent their opponents or the Grimm from finishing them off while they were unconscious, but that's why they tried their best to win.

Aura creates an interesting dynamic to fights for me: on the one hand, the attacker will fight all out even if they don't want to kill, because their opponents Aura will protect them from lethal damage; while the the defender will try their best to not get hit, because their Aura will not always protect them. You see, whenever someone's Aura reflexively activates to shield the user from damage, it is reduced, and after getting hit hard enough and enough times it runs out, leaving them exhausted or even helpless(a little like a fight without Aura). And even with Aura, getting slashed with a sword or punched in the face hurts(again, like a fight without Aura).

I can understand why you might want to add a "Kryponite factor" to negate Aura, though: It's hard to write with. Because there's little visual feedback, it's hard for the audience to gauge how much danger the characters are in. It's probably the reason why many fanfics just leave it out(which is fine); and why I'm having so much trouble with my analysis/re-write of Breach. Still, I think that if you're making a story that includes Aura, you should try and work with it instead of trying to find contrived ways to work around it.

Take that analysis/re-write I was talking about earlier - I have found Aura to both a curse and a blessing in it. For instance, I can't really do something like have Blake getting a cut on her cheek to show how close the Grimm are to hitting her; on the other hand, I could do something like have a King Taijitu chew on Ruby right before Nora Magnhild's its face in, leaving Ruby unharmed but weak - possibly helpless for a little while. It doesn't have to be anything that extreme, though; just having characters getting hit and staggering in pain can have the intended effect of increasing tension. You will probably need some cakewalk fights where no one gets hit as a counterpoint these ones where they do, though.

More importantly though, I don't think you've properly thought out all repercussions of having a Grimm that can straight-up nullify Aura - For instance, the weapons of Hunters are conduits for Aura, meaning that much of their durability and sharpness is due to Aura(see: the baguettes from Best Day Ever); This means that this Grimm could smash weapons with ease. And how would it even be capable of negating Aura anyways? Aura is a manifestation of the soul to protect the body; is this Grimm some kind of "Soul Eater"? How come it doesn't "steal the soul" on touch? Why would such a thing even exist? And what effect would this type of Grimm have on the war - especially if it appears en-mass?(it's not obvious, but the Grimm have more-or-less "trapped" humanity within the Kingdoms' walls)

And that's not getting into how it could effect the fights - the only dramatic fights would be against these Grimm, while all the rest of the fights would lack tension due to a lack of apparent threat. You'd then have more Grimm with this ability show up just to maintain the tension, until they become "normal"; leaving you with a situation similar to having different levels of Grimm fighting people with Aura - or just removing Aura shields entirely.

Look, I'm assuming you're looking for some advice for a fanfic(which is fine by me), and I'm not going to tell you that you can't use the Aura-piercing Grimm in it. But I think you might want to try looking to other ways of showing the mortality of Hunters. Failure is a good place to start: failing to complete a mission; failing to save a village; failing to protect themselves. Have them be overwhelmed, beaten down, disarmed, even wounded(just be sure to show the recovery from those wounds). Have them rush in over their heads and need to be rescued. Have someone who tried to save them get injured or even killed. You can also look to your World-Building to aid you in this: How strong are the Grimm? You can make it so that even a handful of "weak" Grimm are a big threat; or you can have swarms of hundreds overwhelm Hunters; or some of both. What are the Grimm? Where do they come from, and why do they exist(you don't need to explain this to your audience, not at first. Just keep it in mind.)? Aura shields: You can use them as is, or change them to better suit your story, or even remove them entirely(as a said, it's almost an unspoken rule that you can do that in RWBY fanfics). The Aura-piercing Grimm: how does it relate to Aura and the rest of the Grimm? What role does it serve not just in your story but in your world?

This is all just advice; you're free to use, modify, or ignore any and all of it. It's your choice. But I hope I've given you some ideas for how to improve your work. Unless you aren't making a 'fic. In which case I apologize profusely for wasting your time with my gigantic post!