According to the ingame tooltip of Excruciating Strike (Destroyer skill), it can deliver a critical hit: Attacks the enemies in front of the character with 465 Power added to P. Atk. Decreases the enemy's P.Def. by 20%. Requires a sword/two-handed sword. Over-hit and Critical are possible. Ignores Shield Defense. I have used the skill 300+ times, no crits whatsoever. Please, look into it.