*You gain your very own Keyblade just like the ones from Kingdom Hearts. It's default form can be anything from the games as long as it isn't Ultima Weapon (or Omega Weapon), or even something original of your own design.
*A body just above the peak of your species in ability, one sculpted to your tastes and tougher then it should be. This body can grow in ability and durability through training.
*You gain the ability to use any magic seen in the series, but you start out knowing how to use none of it. Your magical reserves start out small, but grow over time when frequently used.
*You gain a downright supernatural ability to learn practical skills 'on the job'. Whenever you face a difficult trial and succeed, you will be able to derive a spell or technique relating to the challenge in question at a level slightly below that of the challenge itself. For example defeating a powerful fire demon would grant you Fire, Fira, Firaga, or even higher levels of fire magic should the threat be great enough. While fighting skilled swordsmen would allow you to emulate their techniques with your Keyblade. You can even develop Keyblade Transformations on your own once you reach a high enough level, and if you fight opponents with similarly transforming weapons.
*Speaking of Keyblade Transformations, if and/or when you develop the ability to turn your Keyblade into a Glider, you can travel to any fictional setting on it. You're not limited to just Disney or Square-Enix properties.
*Furthermore, you can 'meld' two or more sufficiently mastered techniques and/or spells to create stronger skills and spells. However these new abilities are learned at a base level, and take time and experience to be mastered enough to be melded again.
*When you perform the Keyblade Inheritance Ceremony one someone, you can guarantee that the recipient will one day gain their own Keyblade. This can be toggled.
*You can acquire Keychains to temporarily change your Keyblade's form and abilities, after having a short adventure in another world. Even normal physical objects can also become Keychains if they have enough emotional sentiment attached to them. You also know the recipes to synthesize the various Ultima Weapons (and Omega Weapon), you just need to acquire the materials the old-fashioned way.
*You have a special form of perfect memory with infinite storage that prevents you from being reverted back to 'Level 1' like Sora. Whether its having your memories erased, being in a year-long coma, nearly being possessed by an evil master of darkness, or having to lose them to take an exam. Thus, any powers or skills gained through this Essence will never degrade.
*You also have the capacity to use Light and Darkness, but this Essence provides no protection against the corruptive influences of the latter. That's something you'll have to build up on your own, like Riku did.
*Lastly, you have the knowledge and skill needed to create supplemental equipment like Black Coats, Keyblade Armor, or even the various magic clothes made by the Three Good Fairies.