"small flower," 1811, from French fleurette, diminutive of fleur (see flower (n.)).
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for fleuret
Fleuret meant in Old French a sword-blade not yet polished and hilted, and we find it used, as we do Eng.The Romance of Words (4th ed.)
The foil is called in French fleuret, and in Italian fioretto (literally “bud”) from this button.