nullify vs weaken

nullify and weaken both are verbs.

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

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

nullify (verb)	weaken (verb)
make ineffective by counterbalancing the effect of	become weaker
show to be invalid	lessen the strength of
declare invalid	reduce the level or intensity or size or scope of
	lessen in force or effect
	destroy property or hinder normal operations