There are quite a few things I would add to your payment model, but the largest one is simply giving those that would otherwise never buy anything a taste of what it's like to be fabulous.

I'm talking freebies for everyone. Every time there's a promotion, give everyone a prize box for free. There are obvious technical details making this harder, but I'll get to those later. You give the the prize box because it equalizes everyone over time and because it's how you breed paying players. Without it, many people will never understand that what you're selling is worth buying due to the stigma against microtransactions. It also does wonders for your PR, which isn't necessarily bad but has certainly been damaged by the lack of updates and numerous prize boxes you've released.

Now. In order to receive your prize box you must have a certain amount of time in game played on one knight, say 100 hours or so, and a unique IP address. This way, it's harder for alt accounts to collect boxes. The boxes and accessories could also come bound if need be. This way, you don't have people selling whatever they get immediately, and the costumes they get would be impossible to sell while the accessories they get would at the very least be more expensive to sell. There are other ways to deter, but it might be worth giving to people just verbatim without much hassle with trading, since letting them profit off of their unwanted goods would be a part of the experience.