Passive Voice: "one" as object of action
When one has been wronged, a vigorous defense must be mounted
In this sentence, the verb "to wrong", meaning "to do something bad to someone", is used in the Passive Voice.
John wronged Jim. (Meaning: John did something wrong to Jim)
Here, the same verb is used in the active voice. Let's remodel to the passive voice:
Jim was wronged by John. (Meaning: John did something wrong to Jim; the verb is in the Passive Voice)
Here, the meaning is the same. We can change was to has been, shifting the tense from Past Simple to Present Perfect:
Jim has been wronged by John. (Meaning: John has done something wrong to Jim)
Finally, we can remove "by John", because the Passive Voice makes emphasis on what has happened to a person, and this makes the mention of the agent (John) less important:
Jim has been wronged. (Meaning: Someone has done something wrong to Jim)
Active voice: "one" as agent
In a crisis when one has done wrong, wrong repentance is required.
Here, the Active Voice is used. The meaning is: Someone ("one") has done something wrong, hence, a repentance is required.