blunt vs weaken

blunt is an adjective but weaken is not an adjective.

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

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

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

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

Other hyponyms of blunt include obtund, petrify, break, damp, dampen, soften.

blunt (adjective)	weaken (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

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