Feather tights

Feather tights is the name usually given by art historians to a form of costume seen on Late Medieval depictions of angels, which shows them as if wearing a body suit with large scale-like overlapping downward-pointing elements representing feathers, as well as having large wings. Other sources use feathered angels to describe the style. The style is assumed to derive from actual costumes worn by those playing angels in medieval religious drama, with the "feathered" elements presumably flaps or lappets of cloth or leather sewn onto a body suit. The feathers on angels in art can often to be seen to stop abruptly at the neck, wrists and ankles, sometimes with a visible hemline, reflecting these originals.

Historians of English churches tend to refer to the style as 15th century, and by implication essentially English, but it can be seen in several major late medieval European works from the late 14th to early 16th centuries...

It is believed that this practice arose from medieval liturgical dramas and mystery plays, in which the actors portraying angels wore garments covered with feathers to emphasize their power of flight, often standing on "clouds" of wool. Feathered tights are not to be confused with the feathers of the extra pairs of wings traditionally attributed to cherubim and other higher orders of angels, which are often shown pointing downwards covering the legs... 

More information at Wikipedia, where there are links to additional images.