I bought a pleather catsuit for my catwoman cosplay.
Its not as shiny as the pleather I bought for the hat.
I would like to know how to dull out the pleather for my hat a bit? If possible

Having initially wanted a pair of cheap fancy dress 'go-go' boots for my Lady Sif costume, but finding them only coming in patent red I can testify that gloss PVC is a pain in the backside.

I wound up trying the acetone nail polish remover and a scrubby sponge trick on an old handbag and it sort of worked (it maybe took the gloss down a shade).

It wasn't the matte look I was after but if all you need is slightly less shine, it might be worth a shot. I just used any old nail polish remover and a standard green/yellow dish sponge. Try somewhere inconspicuous/on something scrap first.