negate vs weaken

negate and weaken both are verbs.

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

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

negate (verb)	weaken (verb)
make ineffective by counterbalancing the effect of	become weaker
prove negative; show to be false	lessen the strength of
deny the truth of	reduce the level or intensity or size or scope of
be in contradiction with	lessen in force or effect
	destroy property or hinder normal operations