"Esquire" and "Sir" are not titles of nobility. They are references to peerage, a step below nobility. If memory serves, "Baron" is the lowest of the noble ranks.
Lawyers are noble? I can't get over this oxymoron. I've never met a noble lawyer.
The five orders of nobility, from most to least exalted, are Duke, Marquess, Earl, Viscount and Baron.
Below them are the Baronets (hereditary knighthood) and Knights. An Esquire is properly an attendant on a knight; the title is vocational and in course of time an esquire could expect to become a knight. Any other use of the term is a modern abuse (dating from the 16th century or thereabouts).