weakness vs impuissance

weakness and impuissance both are nouns.

Word	Noun	Adjective	Verb	Adverb
weakness	Yes	No	No	No
impuissance	Yes	No	No	No

As nouns, weakness and impuissance are synonyms defined as:

Other synonyms of weakness include helplessness.

weakness (noun)	impuissance (noun)
the property of lacking physical or mental strength; liability to failure under pressure or stress or strain	powerlessness revealed by an inability to act
powerlessness revealed by an inability to act
a penchant for something even though it might not be good for you
a flaw or weak point
the condition of being financially weak