Definitions for "Petty"
Little; trifling; inconsiderable; also, inferior; subordinate; as, a petty fault; a petty prince.
inferior in rank or status; "the junior faculty"; "a lowly corporal"; "petty officialdom"; "a subordinate functionary"
(informal terms) small and of little importance; "a fiddling sum of money"; "a footling gesture"; "our worries are lilliputian compared with those of countries that are at war"; "a little (or small) matter"; "Mickey Mouse regulations"; "a dispute over niggling details"; "limited to petty enterprises"; "piffling efforts"; "giving a police officer a free meal may be against the law, but it seems to be a picayune infraction"
From the French "petite" or "small" refers to a wide range of smaller Western style kitchen knives that we would call parers or utility knives.