derogator

a. Tending to derogate, or lessen in value; expressing a low opinion; expressing derogation; detracting; injurious; -- with from, to, or unto.
Syn. -- belittling, depreciative, deprecatory, depreciatory, derogatory, detractive, detracting, slighting, pejorative, denigratory. [ 1913 Webster ]

Acts of Parliament derogatory from the power of subsequent Parliaments bind not. Blackstone. [ 1913 Webster ]

His language was severely censured by some of his brother peers as derogatory to their other. Macaulay. [ 1913 Webster ]

Derogatory clause in a testament (Law), a sentence of secret character inserted by the testator alone, of which he reserves the knowledge to himself, with a condition that no will he may make thereafter shall be valid, unless this clause is inserted word for word; -- a precaution to guard against later wills extorted by violence, or obtained by suggestion. [ 1913 Webster ]