The phrase "petty tyrant" refers to a person who has a small amount of power but abuses it by being controlling, oppressive, or unfair. Full definition
Says Stossel «I thought they were heroic animal rescuers, but some animal owners say they act like petty tyrants, confiscating animals that aren't in trouble. (thedogplace.org)
I'm not sure that this is an argument for the end justifying the means, but there doesn't seem to be an upside to a world were Roman cruelty is replaced by the cruelty of all the classical worlds petty tyrants and warlords. (nakedpastor.com)
-- The other aspect of the conquest period — the tendency to disunion under petty tyrants — could not last, or the Hebrew people would soon have perished in civil war or become prey to their powerful neighbors. (religion-online.org)