Variety of Rewards, Pets, Armours, Weapons, Cosmetics, and Unobtainables.
If items are non-cosmetic and are valued as Very Rare, 99% of the time they're the best of its category!
Some quantities are based on the amount globally, and some are N/A meaning there is too many to estimate, or there is none ingame. However those will be listed under Very Rare. There are some items that are non-obtainable anymore as they are removed from the game except for current ones!