mercifulness vs lenity

mercifulness and lenity both are nouns.

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

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

Other hyponyms of mercifulness include compassion, pity, forgivingness, kindness, lenience, leniency, mildness.

mercifulness (noun)	lenity (noun)
leniency and compassion shown toward offenders by a person or agency charged with administering justice	mercifulness as a consequence of being lenient or tolerant
a disposition to be kind and forgiving
the feeling that motivates compassion