I thoroughly enjoyed "Kishido: The Way of the Western Warrior" by Peter Hobart. The book can be read pretty quickly. It contains 50 short chapters in 161 pages and then includes a short Glossary of Japanese terms used in the book as well. While the chapters are short, the contain some very important lessons.
The book is a series of lessons that Hobart's martial art master passed to his students while not only teaching martial arts, but teaching virtues embedded in all traditional martial ways. The instructor taught through example that conduct is just as important as ability. He exemplified integrity, dignity, courtesy, chivalry, truth, trust, benevolence, and wisdom. He passed these lessons to his students, and now Hobart has written them down so the reader can blend the philosophical and spiritual concepts found in martial arts with the physical and technical training of their specific art.
The lessons are categorized in five parts: Foundation, Range, Strategy, Harmony, and Void. There are ten chapters in each section, and they cover topics such as: Shoshin (An Open Mind), Junshin (A Pure Heart), Fudoshin (A Determined Spirit), Heiho (Strategy), Gi (Right Decision), Yu (Bravery), Jin (Benevolence), Rei (Right Action), Makoto (Truth), The Dao (Interconnectedness), and Girei (Professional Courtesy).
There are quite a few topics with quite a range of lessons. I think some of the most important are illustrated in the final chapter, those of gi, yu, jin, rei, makoto, meiyo, and chugi; or Right Decision, Bravery, Benevolence, Right Action, Truth, Honor, and Loyalty.