Ministry of Penance

Are you referring to Minister of Penance, a San 'Shyuum Legate of the Covenant who served in the Second Battle of Harvest? The Ministry of Penance is part of the Covenant's Council.

Meaning
Penance is repentance of sins as well as the proper name of the Catholic and Orthodox Christian Sacrament of Penance and Reconciliation/Confession. The word penance derives from Old French and Latin poenitentia, both of which derive from the same root meaning repentance, the desire to be forgiven. This considered, it is highly likely that the Ministry of Penance deals with the justice system within the Covenant.