Regarding the significance or meaning of any particular charge (or colour) in a coat of arms, the MFAQ (Most Frequently Asked Questions) at Francois Velde's "Heraldica" website notes:
"The short answer is that there are no systematic meanings assigned to the
charges and tinctures in arms. There is no way to look at a set of arms
and decypher the original designer's intended symbolism."
If you'd like more detail, you can read the entire MFAQ at
http://www.heraldica.org/faqs/mfaqDavid