Explain the symbols that represent the theme of "loyalty versus betrayal" in the play Othello?

In Othello, the major symbols that
represent the dualities of loyalty and betrayal are the rank of Lieutenant, the
handkerchief, and, quite simply,
words.

• Rank of
  Lieutenant:

Iago is insanely
jealous that he was passed over for this rank.  How could Othello give the rank to a
younger, less experienced bureaucrat like Cassio?  As a result, Iago hates the Moor and
vows revenge.  In his plan, Iago gets Cassio drunk and into a fight so that Othello
strips Cassio of the rank, leaving it an open position for Iago to fill.  So, by the
end, the disloyal Iago aligns himself with Othello, and they plot to murder both the
loyal Desdemona and loyal Cassio.  Dramatic irony at its
finest.

• The
  Handkerchief:

"There's magic in
the web of it."  The handkerchief is a symbol of morbid love and jealousy to Othello.
 Whoever is in possession of it is also in possession of Othello's extreme emotions.  It
is a magical kind of puppet-master that controls loyalty and betrayal throughout the
play.  Everyone has his hands on it: Othello, then Desdemona, Emilia, Iago, Cassio, and
Bianca.  It goes from a loyal lady to a prostitute, and when Othello sees it in
possession of a woman other than Desdemona, he vows to kill his wife for
infidelity.

He who controls language controls others.  Like
the devil in the Garden of Eden, Iago uses words to tempt his subjects.  His words
publicly seem to be honest, but privately we and Roderigo know they are lies.  Othello
calls Iago "honest" throughout the play, a word synonymous with loyalty.  By baiting
Othello toward jealousy and murder, Iago successfully takes away language from the Moor
and causes him to become a mute beast.  This "Beauty and the Beast" is no fairy tale
that ends happily ever after.