The most authoritative general reference on the history of heraldry and its modern usage, The Oxford Guide to Heraldry offers more than 200 pages on the origins and spread of the art, its rules, uses, and authorities, and includes many fine plates depicting actual heraldic rolls and other period images.
It really is a complete book of heraldry, or as close to it as you can get for such a concise volume. Anything not covered by Slater is something you really don't need to know -- unless, of course, you are obsessed with the subject, in which case, you should buy more than one book of heraldry! At the very least, this is an excellent introduction.
Clarity of presentation is sacrificed for volume in this jam-packed work. Addressing all aspects of heraldic design and containing dozens -- and dozens -- and dozens of images, this book is not for the beginner, but it is an absolute must-have for the enthusiast. Unfortunately, it's hard to find. Fortunately, the power of the Internet can help you by visiting the link below. And be sure to also check out Neubecker's more recent work, A Guide to Heraldry.
Oddly enough, I don't consider this book very useful as an introduction to Heraldry -- it begins by depicting some of the most complicated designs extant today without fully explaining the idea of marshalling (bringing together different designs on one shield) until much later in the book. But there is still a lot of useful stuff here, even if the layout is a little crowded.
The copy I have on my shelf is much older than the nice clean reprints that came out a few years ago, and well worn, because it is almost as useful today as when it was first published over 100 years ago. Fox-Davies is extremely thorough, covering every possible component of heraldic designs and appurtenances, as well as offering a little history and an evaluation of the status and meaning of coats of arms in Great Britain at the time. Of course, it's important to keep up-to-date on recent scholarship, and no true heraldry aficionado should stop at Fox-Davies; but I'm glad to have him on my bookshelf, and I think you'll be glad, too.
What collection of heraldry books would be complete without clip-art? This isn't my only heraldry clip-art book, but it is by far the best. The designs are beautiful, imaginative, and for the most part quite clean. Scan them for use on your computer, or photocopy them for kids to color.
This little booklet is perfect for designing your own coat of arms, whether you're a professional looking to create something different for an art project or a child learning heraldry for the first time. It includes templates for shields, charges, mantling, scrolls and much more, as well as information on national heraldry for different countries and medieval blazonry. Both fun and informative, no heraldry fan should be without it.