Shock Stun Success Rate (Based on Level)
Shock Stun: Can only be used when the player has a two-handed sword equipped. Shock Stun has a random duration from 1 to 4 seconds.
For every 5 points of Stun Resistance, your chance to be stun, by the same level character, decreases by about 4% to 5%.
Shock Stun Influences (STR, Weapon)
Although it has been confirmed "Sword of Destruction", "Great Sword of Independence", and "Sword of Orisis Thebes" offer slightly varying stun success rates, 40%, 39%, and 42% respectively. There is no significant advantage between either weapon.
Strength has no effect on the success rate or duration of Shock Stun.