Gives you a chance to do a little damage whenever you parry. Unless it’s been uptuned significantly in recent years, this skill no substitute for the attacks you lose by parrying in the first place.

The in game help reads:

Skill duration: random.
Type of skill : neutral skill.
Affecting stats: Str/Dex.
It uses no endurance points.
Those fighters who practice a defensive style of
fighting do not limit themselves to defensive tactics.
Once they possess the ability to parry attacks, they gain
the ability to counterattack. By throwing their opponents
attack to the side, they are able to complete the move by
hitting their opponent, who is still in mid-thrust. Fighting
someone who has mastered this technique can be frustrating,
besides deadly.