The Collaborative International Dictionary
martel de fer
martel de fer \mar`tel` de fer"\ [OF., hammer of iron.]
A weapon resembling a hammer, often having one side of the
head pointed; -- used by horsemen in the Middle Ages to break
armor.
--Fairholt.
Wiktionary
martel de fer
n. A weapon resembling a hammer, often having one side of the head pointed, used by horseman in the Middle Ages to break armour.