First, I would try and put the thick outer jacket pieces back to their original form, then wrap the cable with quality electrical tape, 2-3 inches above and below the damaged area.
Then get some thick sports tape and wrap it making a bulge where it rubs the most.
Next, get some small wire ties and put a half dozen on the cable where it rubs so it does not touch the twist clamp, cut off excess wire tie.
Lastly, I would file down the twist clamp edge/threads a bit to make it smoother where it rubs the cable.