At what point did Batman strengthen his lines?

I saw the film “Batman: Under the Redhood” and Batman asked Grayson “Do you know how many knives can cut my line?” And when Grayson said not many, he replied “No, not many.” Jason used the knife btw.

Then I saw a clip from Batman vs Teenage Mutant Ninja Turtles where he and Shredder interacted the first time and Shredder cut his line

Did he decided to improve his grapple line after the Jason interaction? Or was there another time?