This image of simple geometry is ineligible for copyright and therefore in the public domain, because it consists entirely of information that is common property and contains no original authorship.
The composition of coats of arms are generally public domain with respect to copyright laws, and may be reproduced freely.
This corresponds to the international traditional usage, and is explicitly stated in some national copyright laws. Some compositions, of more recent origin, may be copyrighted.
This is not a valid license as such, being a "public domain" statement for the coat of arms definition only. It must be completed with the copyright tag associated to the picture creation.
Please note that this applies only to the coat of arms definition (composition / description). The representation of a coat of arms is an artistic creation, subject as such to copyright laws.
Restriction of use - Legal notice: Most of the time, the usage of coats of arms is governed by legal restrictions, independent of the status of the depiction shown here. A coat of arms represents its owner. Though it can be freely represented, it cannot be appropriated, or used in such a way as to create a confusion with or a prejudice to its owner.
Usage on Commons: Please provide licence information for the coat of arm representation, information for the author of the picture, and the source if not self-made work.