blur vs weaken

blur is a noun but weaken is not a noun.

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

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

blur (noun)	weaken (noun)
a hazy or indistinct representation

blur (verb)	weaken (verb)
become vague or indistinct	become weaker
make dim or indistinct	lessen the strength of
make unclear, indistinct, or blurred	reduce the level or intensity or size or scope of
make a smudge on; soil by smudging	lessen in force or effect
to make less distinct or clear	destroy property or hinder normal operations
become glassy; lose clear vision