Do you speak/read Chinese? If so, you might be able to find this but if not, it will probably be tough. I have never heard of anyone fencing in Chengdu before.
Right outside the gym there is a fencing school. I’ve seen kids in class there in the mornings. Not sure if people fence there casually though. That’s the only fencing I’ve seen in Chengdu, but I’m sure more places exist.