Artery Strike is a Swordmastery Active Ability that can behead an enemy outright. It is a popular finisher for sword builds, usually paired with Charge to close the gap first.
It is a heavy single-target strike with a chance to decapitate. Weaker enemies are the ones most likely to lose their heads, which ends the fight on the spot.
Find or buy the Artery Strike manual, then spend skill points and time at a road shrine to learn it.
Guides pair it with Charge to close in and stun, then Artery Strike to finish. Perks that refill Activation Charges, like Adrenaline Rush and Walking Fortress, let you use it more often. Do not spam it alone, since a mix of abilities keeps charges flowing.