I’m fairly certain the “rope” in this animation is a beam.
The character and weapon are animated together. The blade is animated to mimic the behavior as if it was being swung by a rope, then they got 2 attachments, parented one to the blade and another to the character’s hand, and put a beam between them.
You can tell it’s a beam because of the segments that are visible when the blade is swung, as well as the flat, 2-dimensional nature of the “rope”.
Hope this helped.