I am the original person who asked this question and can now confirm that once you beat the Decicive Battle map in NG+, Rank 9 leather and rank 9 steel are added to the acolade shop in the first tab. They cost 5k acolades each to start, increasing with each purchase and seem to cap out around 30k each

I'm the original person who posed this question and can now confirm that once you beat the "Decicive bayttle of Guandu" map in NG+, both rank 9 leather and Rank 9 steel are added to the acolade shop on the first tab. They start out at 5k acolades each and seem to increase in price with each purchase until capping out around 30k, making it much easier to experiment with different builds without feeling like you aren't using your best in class gear