A martial artist’s Qi and Blood is naturally the "essence and spirit" spoken of by Taoism. For an ordinary Rank 8 Martial Artist, controlling the flow of one's own Qi and Blood is difficult enough, let alone infusing it into ink and brushwork.
Zhou Tieyi picked up the brush. Wisps of Qi and Blood welled up from the capillaries in his fingertips, flowing down the brush handle and winding around the rabbit-hair bristles like threads finer than the hairs themselves. He then dipped the Qi-wrapped bristles into the ink and set the tip to paper. He had to draw a talisman while simultaneously maintaining the fusion of his Qi and Blood with the ink; it was akin to multitasking.
After a crooked attempt, the Qi and Blood failed to flow consistently onto the paper, resulting in an ugly, misshapen phoenix pattern.
Chapter 91