Board Thread:Questions and Answers/@comment-9826910-20130618064245/@comment-11051098-20130714124826

I don't know. When he saw that Ichigo unconsciously used Blut Vene when they fought, Yhwach said that "it wasa mistake to use a pure Quincy to stop him". It appears Kirge's jail was the factor that awakened Ichigo's Quincy powers.

As far as I understand, from Yhwach's words, an Echt Quincy was needed to awaken Ichigo's powers. Uryû is confirmed to be a Gemischt, so as I understand, he couldn't have done it.

Ryûken could perhaps have done it in some way, since he is an Echt, though.