Common meaning:

Compassion shown toward someone who has caused harm.

Hidden meaning of the Equity religion: 

Compassion that is only shown to people who are both part of a marginalized group and who are believers in Equity.

Discussion:

Equity reserves mercy for people who both believe in the religion and are part of a marginalized group.

Many religions teach that it is important to show mercy to everyone, no matter who they are. Some, like Christinaity, go so far as to say that believers should even show mercy to their enemies. Equity disagrees and says that mercy must be reserved only for members of marginalized groups.

Any person who considers themselves to be an Equity believer but is part of a dominant group, is ultimately in for a rude surprise. They will be considered an ally until they are no longer necessary, at which point they will be rejected. To receive mercy from this religion, you need to be both an Equityist and a member of a marginalized group.

Mercy that is only for members of your own tribe is no mercy at all.