Visier

horsemen had their hose, Helmets and Visiers, a Shield and launce and two swords; the horses were to be covered with armour and every way prepared for battle, […]

Source: wiktionary

Or, the visiers, i.e. the perforated part of their helmets, through which they could see to direct their aim.

Source: wiktionary

pikes, daggers, rapiers, crossbows, single and double-handed swords, javelins, mailed, plated, and scaled cuirasses, visiers, gauntlets, helmets, breast-plates, and cavalry shields, both convex and flat, […]

Source: wiktionary