Ability: no mercy (Warhammer 40.000: Inquisitor - Martyr)

This:
The heroic deeds quest is"the champion of the God Emperor
5 to achieve the level of fame at least three times a week, ie dial 800 honor point and 2 more times to get the glory for the week.
Total after 5 weeks, I it still earned. As a reward we get the ability to no Mercy.
But not abilities in themselves, not as passive it is not.

Question:
Where and how is it activated and what gives?

PS Checked and inglish. In the Heroic deeds I have it counted as completed. Called No mercy Perk, but the choice of perks it is not. There they are in alphabetical order and difficult to miss.