How i can connect a Sword to Right Arm using Motor6d?

Hi guys
How i can connect a Sword to Right Arm using Motor6d?
Example
https://gyazo.com/1a8d3adb30256150ddce4f1b1e4e2c22
Note
I tried this tutorial, but whenever I try it ends up separating the pieces of my sword or returns an error.

mainly, C1 and C0