The etymology of the word swashbuckler is quite interesting. The term comes from the 16th Century and was used to describe a sword-fighting style using a side-sword held in one hand and a small shield called a buckler in the other hand. The opponents often fought raucously and swashed their swords at each other. Hence the term.

Later, the term became more generalized, and now refers to the fearless, romantic, archetypal characters we see in films -- pretty much always sans buckler.