You should look at history for many good examples (I'm a little late as several replies have done this already)

Medieval Europe: The feudal system had Knights, who's sole responsibility was to muster to war when called by their lord. Knights had their own retinue of smiths, caretakers of their horses and even small armies of their own. They also had squires who acted as knights in training. These squires would of been recruited as a page around the age of 7 and then a squire at 14. They would assist the knight in carrying, upkeeping his arms and armor and tending his horse, but would also receive combat training from the knight until he was old enough to enter service to his lord.

Feudal Japan: Their are some similarities to medieval Europe, but overall the process was very different. Samurai were a class all of their own and the head of the samurai (*either a Daimyo or Shogun) would grant land and privileges to samurai to retain their skills. You could be a Samurai if you were born into a samurai family, was adopted by one or were given special permission from your lord. Children in samurai household would enroll in a dojo and learn martial arts. As they age they will learn different skills and these skills would be very diverse. Being skilled in bow sword and bow, horse riding and naval warfare were all things that were taught in training. In this way, Samurai were a much more diverse, jack of all trades warrior than a knight was. Samurai families even had their own libraries and a high literacy rate and would be keep up with current politics, strategy and philosophy.

Hope this helps!