[Rasna]

Originally Posted by Polydamas

Here are the weights of some historical quilted clothing which was worn under armour, most would cover the Torso and Arms in GURPS and are lighter than Padded Cloth in GURPS.

The heavier garments that are quoted in the article weight as much as GURPS Padded Cloth. However, it's not clear if they were worn with other armour. They're still way lighter than a gambeson.

"There were certainly some very heavy garments stuffed with cotton. Documents from Venice from the end of the 13th century say that infantry should wear overgarments stuffed with 8 libbre (probably the libbra grossa of 477 g) of cotton and bearing the sign of St. Mark (Cessi, Deliberazioni del Maggior Consiglio di Venezia, III, p. 17, 406)."

Being an intermediate thing between padding and proper armour, IMO such garments should be considered more "padding" than "armour" and thus give no DX penalty for a single layer, at least if worn with mail and/or if properly tailored to be worn with armour.