"Mercy" is a word in LAW AND LEGAL, ENGLISH

In praotioe. The arbitrament of the king or judge ln punishing offenses uot directly censured by law. Jacob. So, “to be in mercy” signifies to be amerced or fined for bringing or defending an unjust snit, or to be liable to punishment ln the discretion of the court

A blessing regarded as a manifestation of compassion or
favor.

Forbearance to inflict harm under circumstances of
provocation, when one has the power to inflict it; compassionate
treatment of an offender or adversary; clemency.

Disposition to exercise compassion or favor; pity;
compassion; willingness to spare or to help.

Compassionate treatment of the unfortunate and helpless;
sometimes, favor, beneficence.