Jerald didnt try to kill him, he just planned for it if he didn't like Shangs explanation. Shang saw that planning as a breach of trust equal to an attempt on his life.
"You know," Shang continued, "there was one person that I have trusted with my life, but that person betrayed me and wanted to kill me after knowing my secret."
If you can make abominations and bricks from them, i dont see why he can't make his own body. right before this chapter, we learned entropy can make stuff. Then immediately after, the first thing he does is lose his legs.