The user attacks the target with a single physical attack. It seems to be a basic skill of the Swordsman Class.
It can be an upward slash as shown by Sora, or a downward slash as shown by Hardcore Leveling Warrior.
It is implied by Hardcore Leveling Warrior that this attack is based on the strength stat of the user as he was able to make a big dent in the ground when the skill missed. He had a strength stat of 900+.
Sora used this skill on Managerpark38 but it was blocked by his Electric Sword.
Pooh Upooh Recovery
Hardcore Leveling Warrior attempted to use this on Dongchun but he was saved by Scallion Head. The skill left a big dent in the ground.
Sora's Bash blocked by Managerpark38 (Episode 82)
Scallion Head saving Purple Head from HCLW's Bash (Episode 89)