A buckler (French bouclier 'shield', from Old French bocle, boucle 'boss') is a small shield, gripped in the fist; it was generally used as a companion weapon in hand-to-hand combat during the middle ages, as its size made it poor protection against missile weapons (e.g. arrows) but useful in deflecting the blow of an opponent's sword or mace. - from Wikipedia

The noise of swords onto a buckler has lead to the term "Swashbuckling" which has also defined a fictional genre.