The Elder Scrolls Conversion Project; Artifacts of Tamriel: III. Oghma Infinium

The Book of Knowledge was written by Xarxes and it is frequently associated with Hermaeus Mora, the Daedric Prince of fate and knowledge. It is one of the most powerful artifacts in the world, sought by many, but acquired only by a few. The Oghma Infinum

Oghma Infinium
Wondrous Item, Legendary, Requires attunement

This tome has a patchwork leather cover, and appears to contain pages from many different books. The book contains three major chapters, the Path of Steel, the Path of Shadow and the Path of Spirit, but only one of them could be studied by a reader.
The Oghma Infinium appeared in the world many times, and in many places, usually gifted to mortals by Hermaeus Mora. Due to its nature and power, many search for it, often for decades in vain, for the Tome appears in the most unexpected places.
Attunement requires spending 80 hours of studying one of the tome's chapters. You must make a choice which chapter you wish to study, and you must spend these hours reading that chapter. Reading other chapters does not grant you any insight at all.
Finishing reading a chapter will cause the book to grant you a portion of its power, and then disappear, only to reappear somewhere else in Tamriel, waiting for a new reader. Depending on the chapter you read, you will receive the following blessings:

Path of Steel:
Your Strength and Endurance scores both increase by 2, to the maximum of 24. You gain proficiency in all simple and martial weapons, as well as light, medium and heavy armor, plus shields.
Using your attack action, you can make an extra weapon attack. This stacks with the extra attack class features.

Path of Shadow:
Your Agility and Personality scores both increase by 2, to the maximum of 24. You gain proficiency in Acrobatics, Sleight of Hand, Stealth, Deception, Intimidation, Performance and Persuasion skills. Choose two of these skills. You always roll those checks with an advantage.

Path of Spirit:
Your Intelligence and Willpower scores both increase by 2, to the maximum of 24. You gain proficiency in Arcana, Aedric lore, Daedric lore, and Investigation skills. Your spell save DC formula changes from 8 + Spellcasting ability modifier + Proficiency bonus to 10 + Spellcasting ability modifier + Proficiency bonus.

Additonally, you also gain enough experience to advance a level, but only in a class that fits the chapter you chose to study. You cannot gain a level of Mage, after studying the Path of Steel for example.