User blog comment:Xilinoc/Ch. 540 - The Sword Five/@comment-4515326-20130606093939/@comment-4026406-20130606151049

True. So maybe GT is not connected to the fact that his sword (in shikai at least) is probably closer to a Quincy spirit weapon than a zanpakutou. I think Yhwach!Zangetsu, his Quincy powers, were basically suppressing his true zanpakutou, the remnants of White (Hichigo). Maybe it goes a little farther in that Yhwach!Zangetsu was stealing powers from Hichigo?

This is further evident when he meets his Bankai spirit, Tensa Zangetsu looks like a fusion of Yhwach!Zangetsu and Hichigo; maybe they wanted to work together to save Ichigo so they wouldn't die, or maybe Yhwach!Zangetsu forced their fusion and remained dominant. It's probably closer to the latter than the former, because while he was training for Bankai, Yhwach!Zangetsu was the spirit that materialized through the Tenshinkai. I think Yhwach!Zangetsu was simply trying to save his own ass by protecting Ichigo and giving him strength, but did he want anything more from that pseudo partnership?