Aura ITSELF is what is coating the user in the forcefield, it's clearly proven in the promotional video.
Aura does not generate energy to coat the user, it is the energy.
A stand is not your soul, it is a manifestation of your soul.
Narrarator explained that (admittedly anime only),
even Kira appearing as a soul/ghost proves it, if his stand really was his soul, he would look like Killer Queen. He even summons Killer Queen as a spirit, so his soul clearly isn't Killer Queen. Regardless if you label a stand as a "soul", it's clearly not, since you can't have two souls. Having a manifestation of your soul shattered (in this case, a stand) doesn't necessarily mean your soul shatters, it just means that manifestation created has been destroyed.
Aura is not your soul, it is a manifestation of your soul.
Promotional video explained that, P
yrrah explained that as well. To say it is not is incorrect, no matter how you spin it. Having a manifestation of your soul shattered (in this case, aura) doesn't necessarily mean your soul shatters, it just means that manifestation has been destroyed.
Joseph using hamon against a
tangible manifestation is cano. Aura appears as a
tangible manifestation, it's proven when the Grimm, whom lack a soul and therefore aura,
are also able to interact against aura.
Now let me
REALLY spell this one out for anyone who likes to misinterpret shit:
This means
JONATHAN is
able to use hamon against
TANGIBLE manifestations of the soul, which
INCLUDES aura.
There's
no difference between Joseph and Jonathan's hamo (or any hamon, really) aside from maybe proficency and potency, and even that is not too far off. If
Joseph is able to use hamon against tangible manifestations, this means
Jonathan should be able to use it too.