(Sorry for any mistakes with english)
So I was thiking about the Stern Ritters powers when an idea came to me:
We could consider that quincy is any being who had a portion of Juha's soul inserted in him/her, either through bloodline or through some unknown mean that was used to give Azguiaro (an arrancar) his quincy powers. Saying this, till this day we've not been said that quincy heritage can give any other powers than the standard quincy ones, like spirit weapons and blut. Remember the flashback that showed the birth of Loyd and Royd, if I'm well remembered there was nothing saying that they were born in a quincy family. What about if they were just humans born with different powers, by an unkown reason, and that the Auswahlen was meant to collect the portions of Juha's soul to give it to this special humans transforming them in quincies. This would explain what Orihime really is, and what exactly are this crazy powers some quincies have, like Loyd and Royd's mimicry and Äs' fear manipulation.