Essence of the Dragonborn
*You become the Last Dragonborn with all the weight and power that entails.
*You begin having fully mastered the Thu'um and all known dragon shouts displayed and fully able to be used by yourself. Killing dragons and eating their souls can let you create a new shout based on that dragon if it is strong enough or unique enough. Otherwise you can use dragon souls to improve any new shouts you develop through training.
*You have the will of a warrior and could face down an entire bandit lair using sub-par equipment without letting fear or pain affect you. You are still able to tell when something is dangerous though.
*You learn incredibly quickly and can pick up disciplines at a lightning pace to equal masters of an art in months if not weeks. Once you hit mastery this growth seems to plateau out.
*You are what could be considered an 'end game' Dragonborn and inherit a massive amount of experience in a variety of disciplines. Perhaps you are a shout wielding battlemage or sneaky sort who lead the Thieves Guild or Dark Brotherhood. This can either translate just in pure skills and knowledge or can give you the memories of your Dragonborn fully taking possession of their existence. Alternatively you could simply let yourself start fresh and work for all that on your own.
*You have a house of your own design that is fully outfitted and loaded down with treasures from past adventures if you take on the form of your Dragonborn. Crafting materials, plants, and other consumables seem to refill after sometime left alone. You could even have a proper palace as long as it could be built in Tamriel. Hell you might even need a palace for all the loot you might have.
*Gain your pick of any non-unique equipment set you could get your hands on in Skyrim enchanted or not.
*Gain an amulet of Mara that if worn openly will let you marry anyone available and be considered legitimate for whatever legal or metaphysical systems you encounter. Optionally the amulet is modified to let you wed multiple partners with the same benefits. Anyone who sees the amulet will innately know what it means.
*Optionally gain your own loyal band of Dragonguard and a temple to serve as their base of operations. They are yet small in number but you may decide their composition, general character, and other things. They are all loyal and will follow you to the bitter end. You seem to get a small trickly of new promising recruits either made up of either the people of Tamriel or the locals wherever you are.
*Optionally you may be transported to Skyrim and-"Hey you, you are finally awake, you were trying to cross the border right?"