Skills are special abilities that units can possess, each having widely varying effects. Skills appear in Genealogy of the Holy War, Thracia 776, The Sacred Stones, Path of Radiance, Radiant Dawn, and Awakening.
In Genealogy of the Holy War, skills are divided into Soldier skills, which all units in a particular class possess, and Citizen skills, which are inherent to the character and do not depend on their class. Skills cannot be removed or assigned, but Citizen skills are inherited by any children a character has. Skills can also be gained from equipping Rings or certain weapons. For example, the Killer Bow gives the user the Critical skill.
In Thracia 776, skills work much the same way as in Genealogy of the Holy War. There still exist skills that are inherent to a class and skills that are inherent to a character, but since there is no second generation, functionally these skills are treated the same. Skills can now be learned from Manuals or gained from equippable weapons, but Rings no longer give skills. Notably, Pursuit is no longer a skill and all characters can double attack.
In The Sacred Stones, certain classes have associated skills. Skills particular to characters do not exist as in the SNES games.
In Path of Radiance, skills were reintroduced in a more similar way to as in the SNES games. Skills could be learned from scrolls. However, Skill Capacity was introduced as a limit on the number of skills that any one unit could learn. Mastery Skills were also introduced. These were class-specific skills that were only learnable through rare Occult scrolls. Skills could also be removed to free up capacity for new skills, or simply because certain skills had negative effects as well as positive (such as Parity or Tempest).
In Radiant Dawn, the skills system was much the same as Path of Radiance, with limited capacity and scrolls. However, skills could also be removed and reassigned to other units. Skills that a unit joined with did not take up capacity and were dubbed 'innate' skills. However, certain skills could not be removed. Shove and Canto became skills that took up 5 and 10 space, respectively. Mastery Skills from Path of Radiance reappeared. They could not be removed and took up a large amount of space, and were learned automatically on a Beorc unit reaching 3rd tier (Laguz could use a Satori Sign at level 30). In addition, skills could not be removed or reassigned during Part 2.
In Awakening, skills are obtained when a unit reaches a certain level in their current class, depending on the tier their class is. There are also 5 skills that can be obtained via DLC chapters, and certain characters, such as Walhart and Aversa, have unique skills. Because of the Reclassing system, a unit can gather a wide pool of skills from their reclassing options. To balance this, no unit can have more than 5 skills equipped at any one time. However, players can freely choose what those 5 skills are from all the skills a character has ever learned. Children characters can inherit skills from their parents. They will inherit the last skill that each of their parents has currently equipped, even if it's from a class that they cannot reclass into because of their gender. However, skills from Downloadable Content cannot be inherited. There are also 8 enemy exclusive skills, but most will only appear on higher difficulties.