Mercy (n.) can only be performed by single individuals and is incapable of being performed by juries (who serve as the proxy of society) since society an entity which though one would like to be merciful, absolutely cannot be since it only recognizes those virtues that are advantageous to it.
Mercy (n.) is not always about saving. One has been a poor spectator of life if one has not witnessed the hand that kills from mercy.
Mercy (n.) from God is self-pardon misread: the returning love with which a man loves himself appears to him as God's love.
Mercy (n.) is a virtue that incurs loss, so no society can practise it — it belongs to rulers, saying 'I am powerful enough to bear a palpable loss': a virtue related to pride.
Mercy (n.) is justice overcoming itself — the strongest letting debtors go free: 'What are my parasites to me? May they live and prosper: I am strong enough for that!'