enervating vs weakening

enervating is not a noun while weakening is a noun.

Word	Noun	Adjective	Verb	Adverb
enervating	No	Yes	No	No
weakening	Yes	Yes	No	No

As adjectives, enervating and weakening are synonyms defined as:

Other synonyms of enervating include debilitative, enfeebling.

enervating (noun)	weakening (noun)
	the act of reducing the strength of something
	becoming weaker

enervating (adjective)	weakening (adjective)
causing debilitation	causing debilitation
	moderating by making pain or sorrow weaker