mercifulness vs pardon

mercifulness and pardon both are nouns.

Word	Noun	Adjective	Verb	Adverb
mercifulness	Yes	No	No	No
pardon	Yes	No	Yes	No

As nouns, pardon is a hyponym of mercifulness; that is, pardon is a word with a more specific, narrower meaning than mercifulness:

mercifulness: leniency and compassion shown toward offenders by a person or agency charged with administering justice
pardon: the formal act of liberating someone

Other hyponyms of mercifulness include commutation, re-sentencing, amnesty, free pardon, quarter, reprieve, respite.

mercifulness (noun)	pardon (noun)
leniency and compassion shown toward offenders by a person or agency charged with administering justice	the act of excusing a mistake or offense
a disposition to be kind and forgiving	the formal act of liberating someone
the feeling that motivates compassion	a warrant granting release from punishment for an offense

mercifulness (verb)	pardon (verb)
	grant a pardon to
	accept an excuse for