|Azure, on a bend sinister counter embattled argent a bonnacon passant gules, a bordure wavy Or.|
In heraldry, a blazon is a formal description of a coat of arms from which the reader can reconstruct the appropriate image. The visual depiction of a coat of arms traditionally has considerable latitude in design, while a blazon specifies the essentially distinctive elements; thus it can be said that a coat of arms is primarily defined not by a picture but rather by the wording of its blazon. Blazon also refers to the specialized language in which a blazon is written, and, as a verb, to the act of writing such a description. This language has its own vocabulary, grammar and syntax, or rules governing word order, which becomes essential for comprehension when blazoning a complex coat of arms.
The blazon of armorials follows a rigid formula. Every blazon of a coat of arms begins by describing the field (background). In a majority of cases this is a single tincture; e.g. Azure (blue). If the field is complex, the variation is described, followed by the tinctures used. If the shield is divided, the division is described, followed by the tinctures of the subfields, beginning with the dexter end (shield bearer's right, but viewer's left) of the chief (upper) edge.
The principal charge(s) are then named, with their tincture(s); e.g. a bend sinister counter embattled argent.
A bend sinister is an "ordinary" consisting of an broad band extending from the dexter base (viewer's lower left) to the opposite corner known as the sinister chief. In French heraldry, the bend sinister is traditionally used as a cadency indicating bastardy, though some argue it is rather the bendlet sinister . The term sinister comes from Latin meaning left. A line embattled is a square wave, representing the battlements of a castle. If both edges are embattled, the term embattled-counter-embattled (or simply counter-embattled) is used. In this case the lines are parallel. If gaps face gaps, the term "bretess" is used. The tincture argent is silver (one of two "metal" tinctures) and is blazoned white.
The principal charge is followed by any other charges placed around or on it. If a charge be a bird or beast, its attitude is described, followed by the animal's tincture, followed by anything that may be differently coloured; e.g. a bonnacon passant gules, a bordure wavy or.
The bonnacon (bonacon, bonasus) is a mythical animal from Asia. A bull-like monster but with horns that curl inwards, a short mane and a horse's tail. Its horns being useless, it defends itself by shooting its burning excrement at its enemies. The legend may be based on a type of bison in reality. It appears to have been first granted to Richard Chandelor in 1560 as a crest.
The animal was described by Pliny in his Naturalis Historia: "There are reports of a wild animal in Paionia called the bonasus, which has the mane of a horse, but in all other respects resembles a bull; its horns are curved back in such a manner as to be of no use for fighting, and it is said that because of this it saves itself by running away, meanwhile emitting a trail of dung that sometimes covers a distance of as much as three furlongs [604 m], contact with which scorches pursuers like a sort of fire." The Bonnacon is also mentioned in The Aberdeen Bestiary.
In most cases, an animal (beast) charge is assumed to face the dexter (left as seen by the viewer) although there are many exceptions to this general rule depending on the animal. A beast passant (Old French: "striding") walks toward the viewer's left, with the right forepaw raised and all others on the ground. If a beast is blazoned upon a ordinary sinister, it is assumed to face the sinister without having to specifically blazon it so . The tincture gules is red.
A bordure is a band of contrasting tincture forming a border around the edge of a shield. The size of the bordure, as with many other elements of heraldry, is variable. Since it is very often used for cadency rather than to distinguish between original coats, the bordure is not strictly held to the rule of tincture. A bordure wavy is often used to indicate bastardy in England. The tincture or is gold (one of two "metal" tinctures) and is blazoned yellow.
With the blazon "Azure, on a bend sinister counter embattled argent a bonnacon passant gules, a bordure wavy or" anyone can recreate a correct coat of arms image!
 A Guide to Heraldry by Ottfried Neubecker
 An Heraldic Alphabet by J.P. Brooke-Little, Clarenceux King of Arms
 An Introduction to Heraldry by Stefan Oliver
 Basic Heraldry by Stephen Friar and John Ferguson
 Dictionary of Heraldry by Brockhampton Press
 Feudal Coats of Arms by Joseph Foster
 Heraldry Its Origins and Meaning by Michel Pastoureau
 Wikipedia - Heraldry series (http://en.wikipedia.org/wiki/Heraldry) "Used with due caution"
Errata, exceptions, etcetera:
A bonnacon may not be used in registered arms within the SCA as "The bonacon was considered too offensive by a significant fraction of the College and is therefore not allowed for use in the SCA. WVS  [LoAR 21 Jul 80], p. 12". As such, my list shields depict a bull gules with a really long (almost flame like) tail. Bull-gules, beguiles. :)
If certain features of a beast are of a contrasting tincture, the charge is then said to be armed (claws and horns and tusks), langued (tongue), pizzled (penis), attired (antlers or very occasionally horns), unguled (hooves), crined (horse's mane or human hair) of a specified tincture. Since my bonnacon is shown with hoofs and horns or, the proper blazon should be "Azure, on a bend sinister counter embattled argent a bonnacon passant gules armed or (possibly "ungluled or" as well), a bordure wavy or", but that's too much of a mouthful. I am unable to find proper terminology for the tincture of a beast's flaming excrement / noxious gas cloud.
My bordure has been criticized as being too narrow as it was "traditionally one-sixth as wide as the shield itself". I lean towards the equally valid argument "The size of the bordure, as with many other elements of heraldry, is variable. Scottish versions tend to wider than English ones, and a plain one is likely to be narrower than one carrying charges".