You can earn up to 10 ability points by completing quests given by Ability Trainers in Tessetio and Unite. You can learn abilities by reading books, and they can be purchased with medals from Ability Trainers.
Ability Window

HotKey [ L or l ] toggles an ability window on/off.

This means (Ability points spent) / (Maximum ability points).
Unlike skill points, the ability points spent increase up to 3 points based on the level of ability you learn.

Every character has default abilities. Default abilities do not spend any ability points, and they cannot be erased.

Common abilities require 1 Ability Point per ability while Professional abilities require 1 Ability Point for an apprentice level ability, 2 Ability Points for a journeyman level ability, and 3 Ability Points for a master level ability.

Common Abilities
Provides more respawn points. It is a must have ability for adventurers who die very often. You can use additional respawn points
More respawn points
Transport Master
Extends the time limit for using temporary inventories. It is useful for adventurers who worry about dropping items while hunting or moving.
Extended Time : 7 Minutes
Membership Card
Allows you to buy cheap items and sell for a higher profit at stores. This has no effect at black markets.
Membership Bonus : 10 %
You will be rich!
Increases the gold amount dropped by monsters. It is useful to earn more gold from hunting.
Gold Drop Rate 100% Up
Turns three identical potions into its higher potion by mixing them with a higher level Alchemist Water.
3 Identical Potions + 1 Higher Grade Alchemist Water >> 1 Higher Grade Potion

Professional Abilities
Increases a chance of successful upgrading. It also reduces the costs of upgrading and stat-transferring.
ApprenticeSuccessful Rate + 5%, Upgrade/Stat-transfer Cost - 5%
JourneymanSuccessful Rate + 15%, Upgrade/Stat-transfer Cost - 15%
MasterSuccessful Rate + 30%, Upgrade/Stat-transfer Cost - 30%
Turns three identical gems into a more valuable gem. It also increases the gem drop rates.
Apprentice3 Chip Gems + 1 Fehu >> 1 Small Gem, Gems Drop Rate + 25%
Journeyman3 Small Gems + 1 Othila >> 1 Normal Gem, Gems Drop Rate + 50%
Master3 Normal Gems + 1 Jera >> 1 Perfect Gem, Gems Drop Rate + 100%
Turns two identical accessories into a higher grade accessory. It also increases the accessory drop rates.
Apprentice2 Identical Accessories >> 1 Higher Grade Accessory, Accessory Drop Rate + 25%
Journeyman2 Identical Accessories >> 1 Higher Grade Accessory, Accessory Drop Rate + 50%
Master2 Identical Accessories >> 1 Higher Grade Accessory, Accessory Drop Rate + 100%
Increases a chance of looting your class equipment. It also increases the equipment drop rates.
ApprenticeEquipment Drop Rate + 10%, My Class Equipment Drop Rate + 10%
JourneymanEquipment Drop Rate + 20%, My Class Equipment Drop Rate + 20%
MasterEquipment Drop Rate + 30%, My Class Equipment Drop Rate + 30%
Refines metals for upgrading equipment. It also increases the metal drop rates.
Apprentice1 Silvin + 10 Bronze Dusts >> 1 Refined Silvin, Mineral Drop Rate + 25%
Journeyman1 Mithril + 10 Silver Dusts >> 1 Refined Mithril, Mineral Drop Rate + 50%
Master1 Iternium + 10 Gold Dusts >> 1 Refined Iternium, Mineral Drop Rate + 100%
Allows harvesting expensive minerals, and powders that can be used to refine metals.
ApprenticeMinable : Chip/Small Gems, Silvin/Mithril, Silver/Bronze Dust
JourneymanMinable : Small/Normal Gems, Mithril/Iternium, Silver/Gold Dust
MasterMinable : Small/Normal Gems, Mithril/Iternium, Silver/Gold Dust
Allows gathering various medicinal plants that can be used with Alchemist Water to create potions.
ApprenticeGatherable : Withered and Moist Plants
JourneymanGatherable : Withered, Moist and Vibrant Plants
MasterGatherable : Withered, Moist, Vibrant and Mystical Plants
Spice up the foods from General Store to restore more HP and MP.
ApprenticeEmpty Cruet + Withered Plant >> Mild Spice, Mild Spice + Food >> Mild Spicy Food
JourneymanEmpty Cruet + Vibrant Plant >> Strong Spice, Strong Spice + Food >> Strong Spicy Food
MasterEmpty Cruet + Mystical Plant >> Aromatic Spice, Aromatic Spice + Food >> Aromatic Spicy Food
In order to gather or mine, you must use the gathering skill or mining skill after registering the gathering skill or mining skill into quickslots.