mercifulness vs clemency

mercifulness and clemency both are nouns.

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

As nouns, mercifulness and clemency are synonyms defined as:

mercifulness and clemency: leniency and compassion shown toward offenders by a person or agency charged with administering justice

Other synonyms of mercifulness include mercy.

mercifulness (noun)	clemency (noun)
leniency and compassion shown toward offenders by a person or agency charged with administering justice	leniency and compassion shown toward offenders by a person or agency charged with administering justice
a disposition to be kind and forgiving	good weather with comfortable temperatures
the feeling that motivates compassion