I could literally talk to people like Vaazk, Ashur, Ezio, Kodak, etc. and get 20 hats put together for spar/PK milestones if that's what is preventing this from happening
I'm sure they'd want the hats or some sort of other compensation for their work, but yeah

if I had my way though, it'd be done like this: there is some place that you go to on the map where you can see the spar/PK hats on display, and you can also redeem them by clicking on them when you have the required PKs or wins
each hat comes in 3 different colors that the player can select 1 of, so that it gives players a little bit of customization and variety instead of, "yeah, I got that 20k spar wins hat that everyone else has"

that's me being insanely optimistic though
at this point though, I'd be happy with the bare minimum of getting this done because all I really care about is that more people will participate in sparring/PKing and it'll make the game a bit more fun for a while