Board Thread:New on Bleach Wiki/@comment-27120311-20151025235010/@comment-8986886-20160116134150

Also his Getsuga Tenshou. It's nature seems more quincy than shinigami. After all the basics are the same. A quincy gathers reishi and uses his or hers reiatsu to compress and manipulate the reishi to form the bow and arrows. Ichigo zanpakutou fed on his reiatsu compressed it on the sharpest point of the blade and then released it in a linear attack. It was only during bankai that his Getsuga Tenshou acquired hollow traits, just like Ulquiora pointed out when he compared black Getsuga Tenshou with Cero Oscuras.

Don't forget that Isshin also uses Getsuga Tenshou and he doesn't possess any Quincy or Hollow powers (afawk anyway). That means that Ichigo's Getsuga originates from his Shinigami powers and is fundamentally a Zanpakutou technique.