I'm not sure if this is a translation error, or a mechanics error. However, Combat Inspiration says that it provides a 5/10/15% chance to parry with a 1h weapon equipped.
This is rank 0 Combat Inspiration, with the expected 0% parry rate.
This is rank 1 Combat Inspiration. 70 parries out of 3216 attacks, 2.18% parry rate as compared to the 5% expected.
This is rank 3 Combat Inspiration. 423 parries out of 5385 attacks, 7.86% parry rate as compared to the 15% expected.