weaken vs blunt

weaken is not an adjective while blunt is an adjective.

Word	Noun	Adjective	Verb	Adverb
weaken	No	No	Yes	No
blunt	No	Yes	Yes	No

As verbs, blunt is a hyponym of weaken; that is, blunt is a word with a more specific, narrower meaning than weaken:

As verbs, blunt is a hypernym of weaken; that is, blunt is a word with a broader meaning than weaken:

weaken: lessen in force or effect
blunt: make less lively, intense, or vigorous; impair in vigor, force, activity, or sensation

Other hypernyms of weaken include deaden.

weaken (adjective)	blunt (adjective)
	characterized by directness in manner or speech; without subtlety or evasion
	used of a knife or other blade; not sharp
	having a broad or rounded end
	devoid of any qualifications or disguise or adornment

weaken (verb)	blunt (verb)
become weaker	make less sharp
lessen the strength of	make less intense
reduce the level or intensity or size or scope of	make less lively, intense, or vigorous; impair in vigor, force, activity, or sensation
lessen in force or effect	make dull or blunt
destroy property or hinder normal operations	make numb or insensitive