Adjectives

(s)diminished, lessened, vitiated, weakenedimpaired by diminution
(s)weakenedmade weak or weaker
(s)attenuate, attenuated, faded, weakenedreduced in strength“the faded tones of an old recording”
(s)cut, thinned, weakenedmixed with water“sold cut whiskey”, “a cup of thinned soup”
(s)hurt, weakeneddamaged; used of inanimate objects or their value