This gives you the Knight Rank in game & the Knight Helmet Hat. You can see an image of the Knight Helmet Hat by viewing the image below, equip it in game by using /cm and clicking the Knight Helmet Hat! The Knight Rank grants a Red -> Gray chat gradient in game when equipped. 
You can equip your rank in game by doing /ranks, clicking Cosmetic Ranks and scrolling over to Knight Rank. You CANNOT equip two ranks at once. If there's any issues, feel free to open a Ticket on our Discord describing the issue.