My dog plays with his leash?

My question is NOT how to get him to stop playing with his leash, that can easily be solved. My question is if it's dangerous that he's playing with his leash. It's a vinyl leash with a metal end that clips onto his collar. The thing that you press down to put the leash onto the collar broke off and it's just a small piece of sharp metal now. My dog whips his leash around (playfully) whacking the leash all over the place randomly and aggressively. Does anyone else have a dog who plays with their leash like this? And should I let him do this? If not, is there a safe leash or toy that he could play with instead? (He doesn't whip around heavy ropes cause he's a small breed. A Cavalier King Charles Spaniel whose 6 years old and overweight.)