weaken vs diminish

weaken and diminish both are verbs.

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

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

Other hypernyms of weaken include decrease, fall, lessen.

weaken (verb)	diminish (verb)
become weaker	decrease in size, extent, or range
lessen the strength of	lessen the authority, dignity, or reputation of
reduce the level or intensity or size or scope of
lessen in force or effect
destroy property or hinder normal operations