This book by Karl Friday covers the period prior to the Sengoku period. What is great about this book is how it attempts to reveal what the early samurai were really like, not how they are portrayed in many modern movies or popular culture. Fridays' book overturns many of the popular stereotypes of the samurai.
There are many romantic stereotypes of the samurai such as that during battles, fighting centered on one-on-one duels; or samurai selected suitable opponents during battle by self-introduction; or the honorable treatment of captured enemy or the safety of non-combatants. The common belief that medieval samurai would do anything for their clan.
However, most of these stereotypes are not based in reality. Medieval samurai often used deception or surprise to defeat an enemy. Samurai fought not just for honor but usually for very clear rewards.
One of the biggest myths of the samurai is that the samurai sword was his primary weapon, the soul of the samurai. However, during most of samurai history, it was the bow and arrow that was the true weapon of the samurai. It is true they carried a sword but it was a back-up weapon. Similar to modern soldier whose primary weapon is a rifle but they also carry a sidearm. It was not until the 250 years of peace during Edo period under the rule of the Tokugawa shoguns where the samurai considered the sword to be their soul.
This book does an excellent job in explaining the true aspects of the medieval samurai as well as detailing some of the weapons used during that time.
(Any readers who find inaccurate historical information in this post, please correct me with references)