Steel and Aluminium make great edges and as far as injury is concerned any person can trip on anything really ( and as a kid I was always told to lift my feet)…I don’t think anything provides a sharp edge like steel or alloy can..I found the alloy was harder to keep in a straighter line and needed a lot of fixings, in fact soo much that we designed our own edging and got it made by and alloy extrusion company with extra thickness and in the sizes that needed the minimum number of joins. If your design “needs” a clean edge and your client is keen on the idea surely your boss should be happy that the client gets what it wants??