Ventail

Having unhorsed this enemy and hacked him into submission, the knight rips off his foe's helmet and turns down the mail ventail (protecting the vulnerable throat), perhaps pounds the fellow's face a bit with the pommel of his sword; ...

Finally, the Carolingian byrnie might have had a mail ventail, or bib, hanging from the neck that, when raised and attached to the helmet, provided neck and lower face protection. The ventail is specifically mentioned twice in the ...

[…] depicts the Virtues and Vices in combat. The Vices are trampled underfoo by the victorious Virtues wearing skirts and shirts of mail. Their helmets are bowl-shaped with a mail ventail (ventaille) covering the neck. On a twelfth-century capital in the church of Sainte-Marie-Madeleine in Vézelay, David and Goliath are depicted fighting.

[…] even in the eleveth and early twelfth centuries, where helmets were of a simple nasal form, the wearing of a mail coif with a ventail that laced across the lower part of the face would have covered enough of the face […]

The Lednickie example has its nasal terminating in a small hook; this was almost certainly to support the mail ventail of the mail coif, and thus to provide better facial protection.

Others, most notably David C. Nicolle, claim instead that this merely depicts a mail ventail (the face covering of a mail coif), which has been unlaced for comfort when not in battle.

Then Jessup pulled the chain mail ventail attached to the hauberk over Alaric's head before raising the flap at his throat and tying it on both sides of his face to cover his neck. When his squire handed him his helmet, Alaric settled the ...

A comely knight, all arm'd in complete wize, / Through whose bright ventayle lifted vp on hye / His manly face [...] Lookt foorth [...].

The helmet, in its improved state, was composed of two parts; the headpiece, which was strengthened within by several circles of iron; and the visor or ventail, which (as the names imply) was a sort of grating to see or breathe through, so contrived as by sliding in a groove, or turning on a pivot, to be raised or lowered […]

The rush and ruin of that stroke Latchet and helm and vizor broke; Away the iron ventail flew, Then burst upon the publick view, Death smiling proudly from his face, The last good lord of Monti's race.

To get air for breathing was a serious problem , and records tell us that knights sometimes suffocated in their helmets; for with visor and ventail down breathing was seriously hampered, […]

no ventaille to this darkening / and masked face lifts to grope the air […].

The great bascinet was distinguished by the modification of the mail aventail into a steel ventail. The entire helmet offered excellent protection to the head and neck, including a sleek surface that defended against glancing blows.

398. ventayles : a pun on ventails, 'something acting as a sail or fan', and ventails, the air holes or vents in the vizor of a helmet.

Here would be Sir Gawaine sitting on his antagonist's chest, and finishing him off, through the ventails of his helm, with the long sharp poniard called the Mercy of God. There would be a couple of knights who had suffocated themselves in their own helms during the course of a battle, a misfortune which frequently happened in those days of violent exercise and small vents.