Skills

«Sword Skills» are programmed movements assisted by the system after a player performs the initial movement in «Sword Art Online». Sword Skills are later introduced to ALfheim Online and are also in Underworld. These skills fall into four properties: Thrust, Slash, Pierce, and Blunt. There is also another beginner ability: Final Thrust.

Background
Swords Skills are the basis of combat in Sword Art Online. Skills are activated by beginning the movement of the skill (such as raising a sword above one's head), and then allowing the program to take over and automatically complete the movement and combo. The weapon typically glows a different color when a sword skill is activated.

There are several different classes of Weapon Skills. There are generic weapon skills such as «One-handed Straight Sword»and «One-handed Curved Sword». Then, there are additional weapon skills that can be unlocked after fulfilling a certain set of conditions. For example, in the sword category, the «One-handed Straight Sword» skill must be trained quite a bit before «Rapier» and «Two-Handed Sword» appears on the weapon skills list.

Weapon skills that do not have clear conditions for appearing are called Extra Skills. There are roughly around ten known Extra Skills, including the «Katana Skill» wielded by Klein. Each of these extra skills have at least ten people in the Sword Art Online world who practice the skill.

There are only two known Unique Skills, which are weapon skills unique to a single player. These are Heathcliff's «Holy Sword» and Kirito's «Dual Blades».

Sword Skills are native from Sword Art Online. The system was later added to «ALfheim Online» with minor modifications, including elemental attributes, and allowing the players to create their own skills. It is rumored that about ten skills were removed on the adaptation. However, whether this is true or not has yet to be confirmed.

List of General Skills in Sword Art Online
In general, skills must be equipped in a limited amount of skill slots. Kirito at the end of SAO had 12 skill slots. Skills may be trained up to level 1000, at which it is considered «Mastered». There is rumored to be an unlimited number of skills in Sword Art Online.

Non-Combat Skills

 * Fishing
 * Musical Instrument
 * Sewing
 * Cooking
 * Equipment Appraisal
 * Tools Appraisal
 * Purchase Negotiation
 * Sales Negotiation
 * Medicine Mixing
 * Slash Weapon Forging
 * Thrust Weapon Forging
 * Blunt Weapon Forging
 * Light Metal Armor Forging
 * Heavy Metal Armor Forging
 * Metal Equipment Repairing
 * Metal Refining
 * Familiar Recovery
 * Familiar Communication

Passive Skills

 * Searching
 * Tracking
 * Pursuit - Raises effectiveness while hunting monsters. Can be used to pursue a player whose name is known by displaying their footprints from a certain time, which can be increased with greater mastery of the skill. Requires «Tracking» to unlock.
 * Listening
 * Detection - Prevents ambushes. Greater mastery allows detection of monsters in «Hiding» status.
 * Hiding - Allows for a person to disappear. Only works on targets that use visual tracking.
 * Acrobatics
 * Night Vision
 * X-Ray Vision
 * Sprint
 * Extended Weight Limit

Combat Skills

 * Parry
 * Delay - Interrupts opponents attacks whenever possible.
 * Howl - Attracts the attention of NPC monsters and increases a player's Hate status effect. Often used by Tanks.
 * Battle Healing - Recover certain amount of HP over time during battle. It can be leveled up by constantly getting one's HP into the red zone.
 * Emergency Recovery
 * Meditation - «Extra Skill» Increases HP regeneration and decreases the remaining time of negative statuses by entering a mental concentration pose. Obtained in a 6th floor quest.
 * Light Metal Equipment
 * Light Shield Equipment
 * Leather Equipment
 * Heavy Metal Equipment
 * Spirit Light (hate skill)
 * Fighting Spirit (hate skill)

Weapon Skills

 * One Handed Straight Sword
 * One Handed Curved Blade
 * One Handed Dagger
 * One Handed Rapier
 * One Handed War Hammer
 * Two Handed Straight Sword
 * Two Handed Assault Spear
 * Two-Handed Battle Axe
 * Blade Throwing
 * Martial Arts - «Extra Skill» Unlocked from a quest on the 2nd floor.
 * Katana - «Extra Skill» Unlocked by frequent usage of One-handed Curved Blade.
 * Dual Blades - «Unique Skill» Given to the player with the fastest reaction time.
 * ​Holy Sword - «Unique Skill»
 * Darkness Blade - «Unique Skill»
 * Battoujutsu - «Unique Skill» Means "Sword Drawing."
 * Shurikenjutsu - «Unique Skill» Means "Concealed Weapons."
 * Infinite Spear - «Unique Skill»

One-Handed Sword

 * Slant - (1-hit strike) A simple sword skill slashing diagonally.
 * Vertical - (1-hit strike) A simple sword skill slashing vertically.
 * Horizontal - (1-hit strike) A simple sword skill slashing horizontally.
 * Uppercut - (1-hit strike) A simple sword skill delivering an uppercut.
 * Rage Spike - (1-hit strike) A basic, weak skill that leaps at the enemy and follows with an upward strike.
 * Sonic Leap - (1-hit strike) A charge-type sword skill that dashes toward the enemy to deal a downward strike.
 * Vertical Arc - (2-hit combo) A simple sword skill creating a 'V' shape trajectory.
 * Horizontal Square- (4-hit combo) A mid-level sword skill tracing the shape of a rhombus.
 * Vertical Square - (4-hit combo) A mid-level sword skill tracing the shape of a square.
 * Snake Bite - (2-hit combo) Two left and right swings that target the opponent's weapon, with a chance of breaking the weapon.
 * Sharp Nail - (3-hit combo)
 * Vorpal Strike  - (1-hit strike) A heavy one-handed sword skill with a reach that is double the length of the blade and has high attack power. It has a long cool-down. 30% physical, 30% Fire, 40% Darkness.
 * Savage Fulcrum - (3-hit combo) A sword skill that trace number "4" in the air. 50% physical, 50% Ice.
 * Serration Wave - a single-hit area of effect (AOE) one-handed sword skill, a technique meant to impede movement and barely dealing any damage.
 * Howling Octave - (8-hit) Five high-speed continuous thrusts then cut downward, upward, before another full force upward cut. 40% physical, 60% Fire.

One-Handed Curved Sword

 * Reaver - (1-hit strike) A basic sword skill.
 * Fell Crescent - (1-hit strike) A high-class charge-type sword skill that delivers a downward blow and covers a distance of 4 meters in 0.4 seconds.

Two-Handed Battle Axe

 * Whirlwind - (1-hit strike) A basic spinning strike.

Two-Handed Sword

 * Avalanche - (1-hit strike) A high hitting high-level two-handed sword skill.

Rapier Sword

 * Linear - (1-hit strike) - The first rapier skill learned that delivers a single thrust at the enemy at a great speed.
 * Star Splash - (8-hit combo) - A high-level one-handed thrusting sword skill.
 * Flashing Penetrator - (1-hit strike) - A high-level strike that produces a sonic boom and looks like a comet.
 * Quadruple Pain - (4-hit strike) A rapid four-hit thrust that can immobilize the target.
 * Shooting Star - A charging rapier sword skill.

Dagger
Martial Arts (Extra Skill)
 * Rapid Bite
 * Fud Edge
 * Embracer - (1-hit strike) An unarmed skill that pierces the enemy with the fingers.
 * Flash Hit - «Martial Arts» basic skill.

Katana (Extra Skill)

 * Tsujikaze - (1-hit strike) - "Whirlwind" A straight, long-ranged strike.
 * Gengetsu - (1-hit strike) - "Phantom Moon" A half-circle that moves irregularly.
 * Tsumujiguruma - (1-hit area strike) - An omnidirectional 360-degree whirling spin.
 * Ukifune - (1-hit strike) - "Floating Boat" Knocks opponent high into the air.
 * Hiōgi - (3-hit combo) - "Scarlet Fan" Upward, downward, then thrusting combo.
 * Iai - (1-hit strike) - One of the top techniques of Katana Skill.

Dual Blades Sword (Unique Skill)

 * Double Circular - (2-hit combo) - A dash-type skill that swiftly attacks with the right and left sword consecutively.
 * Starburst Stream - (16-hit combo) - A high-class dual-blades sword skill.
 * The Eclipse - (27-hit combo) - The highest level dual-blades sword skill.
 * Snake Bite - (2-hit combo) - a quick strike that cuts through the opponent from both sides

Holy Sword (Unique Skill)

 * Divine Sword - (1-hit strike) - Releases a strong light from the sword to blind the opponent.

Other Techniques

 * Meteor Break - (7-hit combo) - A seven-hit combo, needing unarmed and one-handed sword skills, that uses tackles to chain together strong attacks.
 * Minimal Side Step Defense - A defensive skill that simply involves an evading side-step. It has higher counterattack speed than parry or block, but it involves greater risks if it fails.
 * Armor Pierce