Board Thread:Off Topic/@comment-24993958-20150629203847/@comment-25396609-20150630031637

As aura is a manifestation of the soul, and semblance is a tangible application if it, that would require you to steal a part of the soul.

Depending on what version of the soul you're looking at (I personally assume RWBY uses the most common, which can be corrupted, but not cut or broken) that would either be outright impossible. or, another of the most common, which can be cut or turn but doing so is IMMENSELY painful, cause horrific agony to the person you steal that bit of soul from.