Rondel dagger A rondel dagger or roundel dagger was a type of stiff - bladed dagger in Europe in the late Middle Ages ( from the 14th century onwards ) , used by a variety of people from merchants to knight s . It was worn at the waist and might be used as a utility tool , or worn into battle or a jousting tournament as a side - arm . Design and construction . The blade was made of steel , and was typically long and slim with a tapering needle point , measuring 12 inches ( 30 cm ) or more ; the whole dagger might be as long as 20 inches ( 50 cm ) . " Rondel " means round or circular ; the dagger gets its name from its round ( or similarly shaped , e . g . octagon al ) hand guard and round or spherical pommel ( knob on the end of the grip ) . The blade ' s tang extended through the handle , which was cylindrical , normally carved from wood or bone . In cross section , the blade was usually diamond - shaped , lenticular , or triangular . These blades would have a sharpened point , and either one or both edges would also be sharpened . They were principally designed for use with a stabbing action , either underarm , or over arm with a reverse grip ( reminiscent of an ice pick ) . They would also have been used for cutting . The long straight blade would not have lent itself to a slashing or sabre action . Rondel daggers were ideal in battle for puncturing chain mail , and although they would not have been able to punch through plate armour , they could be forced between the joints in a suit of armour and helmet s . This was often the only way in which a heavily - armoured knight could be killed . A few examples also exist of four - edged rondel daggers , the blade having a cruciform profile . These blades would not have been suited for cutting , or use as a general utility tool ; they would have been worn as a side - arm in battle as a thrusting weapon , foreshadowing the appearance of the stiletto in the 16th century . Rondel daggers which have survived and found their way into museums and collections are usually those with fine craftsmanship and often ornate decoration . The blades may be engraved , the grips ornately carved , and the hand guards and pommels highly decorated . Usage . The rondel dagger evolves in the 14th century from the early knightly dagger of the 12th to 13th centuries , matching the evolution of full plate armour . By the 15th century it had become the standard side - arm for knights , and would have been carried into battles such as the Battle of Agincourt in 1415 . They were a knight ' s backup weapon to be used in hand to hand fighting , and as such one of their last lines of defense . Since they were able to penetrate a suit of armour ( at the joints , or through the visor of the helmet ) , rondel daggers could be used to force an unseated or wounded knight to surrender , for a knight might fetch a good ransom . In the 15th century , the rondel dagger also rose to popularity among the emerging middle class . In a scene from a miniature by Girat de Roussillon depicting the construction of twelve churches in France ( c . 1448 ) , merchants and tradesmen can be seen wearing rondel daggers at their waists . Hans Talhoffer in his combat manual s of the 1440s to 1460s includes numerous examples of techniques for fighting with the rondel dagger , both in unarmed combat and in single combat in armour .