The enchanting window in Deadfire, showing the enchantment Cloak and Dagger on Azure Blade.
Enchantments in Pillars of Eternity II: Deadfire are modifications that apply special effects to weapons, armor, shields and accessories.
Overview[]
Most unique items (including armor, weapons and shields) are able to be upgraded by enchanting them with new properties and effects. These enchantments may either add new effects, increase the potency of the existing effects, and/or remove a previous enchantment and its effects entirely. Often an item will have more than one upgrade path that you'll have to pick between. For example; Vion-ceth's Wood Splitter enchantment can be upgraded to either Feller or to Wood Bane, but not both.
Unlike Pillars of Eternity, most enchantments are unique to their items (with few exceptions, including quality type enchantments). Only items marked as "unique" can be upgraded with new enchantments. Non-unique items cannot be upgraded, but may still have enchantments.
Enchanting an item is as simple as opening the item inspector and clicking "Enchant" at the bottom of the window. The enchanting interface displays the current enchantments of an item, as well as a possible enchantments that may be crafted. Crafting an enchantment requires a number of ingredients and an amount of coppers (typically 
3,000). The ingredient and copper cost is doubled for two-handed weapons.
Adding an enchantment to an item also increases its value proportionally to the power of the enchantment.