You can also have the same effect if you give cookies 🍪 to Lord Shaxx my experience if you give him more than 10 cookies it gives you legendary gear such as the one shot heavy bow such as the sword master armor. Basically the more cookies you give to those particular vendors the higher chance you have to get these kind of rewards. Who knows maybe this can be applied to all vendors but the trick is you have to give them tons of cookies all at once.