That's an interesting ask... I have always worked to avoid what your looking to achieve but I do like the idea, a lot.
I have never done this but an idea that comes to mind is cutting the edge to a close approximation of the shape your after, then skive off as much as you can get away with.
Then with a leather wrapped mallet, and using a rough rock as an anvil, so the back of the leather is against the rock, hammer the edges to distress it, this will loosen the fibres around the edge and give that fluffy worn look... Possibly... It's only a thought though, I've never tried it.
Do let me know if it works though, I may give it a go.
Nigel