Blood Armor

Blood Manipulation was the ability to control blood as one saw fit. Alex remembered the various objects the blood Song Shing used turned into that he attacked others with.

This was most likely what he was using, or at least a version of it. Alex wasn't sure if freely passing around these techniques in the book was possible or not, so he could only assume the techniques were changed throughout the millennia in the Song family.

Alex looked at the technique and learned about it. While Blood Manipulation was something that affected blood itself, to Alex's surprise, it wasn't the blood that gave it power, but the blood aura.

It was such a small difference that one wouldn't really think about, but when he did learn it, it made sense.

Blood itself wasn't strong, so it would be the blood aura that was more powerful in this case.