Shakespeare's coat of arms is blazoned something like "or, on a bend sable a spear of the first". That is to say, it is yellow with a black stripe going from the upper left to the lower right diagonally, and on that stripe is a golden spear.
Gentlemen At Arms Gentlemen At Arms
Honourable Corps of Gentlemen at Arms was created in 1509.
Since the words "Ladies" and "Gentlemen" were both in his vocabulary, he could have said "ladies and gentlemen". However, these terms in his day were very specific markers of social class. He himself worked very hard to be entitled to call himself "William Shakespeare, gentleman". The only way he was allowed to call himself that was because his father had been granted a coat of arms. You will note that when Viola in Twelfth Night describes her parentage to Olivia she says, "I am a gentleman." That would specifically describe Cesario's social class, a class below Olivia's. Women were often called "ladies" when they were of various social classes. Thus Shakespeare conjoins lords and gentlemen, lords and ladies, and ladies and gentlemen. E.g. "Welcome, gentlemen! ladies that have their toes Unplagued with corns will have a bout with you." (Romeo and Juliet, 1,5)
by standing on your arms straight
He was a gentleman; his father had been given a coat of arms.
Shakespeare used the expression "up in arms" in Henry VI Part II. "The commons here in Kent are up in arms." It means (because its meaning has not changed any) that they have armed themselves and are ready for battle.
Standing on your arms and head
William Shakespeare spent considerable time and money obtaining a grant of arms for his father. That meant that his father had his own personal coat of arms which William (being the eldest son) would inherit on his death. It also meant that he could call himself "Mr. William Shakespeare" or "William Shakespeare, gent."; without the grant of arms he was plain "William Shakespeare."
It is an oft quoted phrase but it is not from any of Shakespeare's plays.
A coat of arms
He was given a coat of arms.
They sleep standing up with their arms spread out.