Extra Skills

«Extra Skills» (エクストラスキル), also known as «Hidden Skills», are the kind of Weapon Skills in Sword Art Online with no clear conditions to unlock them, however, most of these skills have at least 10 known users who are using them. Certain «Extra Skills» are limited to only 1 known user per skill and are therefore called Unique Skills.

Although the exact condition or the quest required to unlock these skills are not publicly known, two known ways of unlocking «Extra Skills» have been revealed so far. Some of these skills are unlocked by training certain regular Weapon Skills, for example, the «Katana» skill appears quite often, as long as the «Curved Sword» skill is trained, while some are acquired as quest rewards, for example, «Meditation» is acquired by completing a certain quest on the 6th floor. Like Weapon Skills, most «Extra skills», including «Unique Skills», have their own special «Sword Skills».

It is said that 10+ Extra Skills have been discovered by the boss battle of the 74th floor, but only 5 Extra Skills have been revealed in the novels so far.

Known Extra Skills

 * «Katana» - unlocked by training the «Curved Sword» skill.
 * «Meditation» - unlocked by completing a certain quest sourced from a NPC exist above 6th Floor.
 * «Martial arts» - unlocked by completing a quest to break a nearly unbreakable rock on the 2nd Floor.
 * All «Unique Skills» - rewarded to players with extraordinary abilities.