The armband is a cosmetic item only that fits in the shoulder slot, and cannot be traded. It normally sells on the Station Marketplace, but SOE has waved the cost for a few days in celebration of Sentinel's Fate's success. You can grab yours by typing /marketplace in EverQuest 2, or by clicking on the Marketplace tab.
Some players have wondered if the armbands were beholden to that one look. As one forum poster asked, "Do they come in any other color than pink?" The response was quick: "Yes, they also come in light red."