weakened vs diminished

weakened and diminished both are adjectives.

Word	Noun	Adjective	Verb	Adverb
weakened	No	Yes	No	No
diminished	No	Yes	No	No

As adjectives, weakened and diminished are synonyms defined as:

Other synonyms of weakened include lessened, vitiated.

weakened (adjective)	diminished (adjective)
damaged; used of inanimate objects or their value	(of an organ or body part) diminished in size or strength as a result of disease or injury or lack of use
reduced in strength	impaired by diminution
mixed with water	made to seem smaller or less (especially in worth)
impaired by diminution	(of musical intervals) reduction by a semitone of any perfect or minor musical interval
made weak or weaker