This months Medieval Warfare is all about Lombards. It features a full page photo of an Italian re-enactor as a Lombard "heavy infantryman". A significant feature is that he wears no metallic armour, but instead wears a thigh length leather lamellar and a leather spangenhelm. Obviously, leather armour would not feature strongly in the archaeological record but do we actually have any evidence for infantrymen in this period armoured completely in leather? Would a leather helmet be made to imitate a metal type, or would we expect something different?
Marco Balbi, in L'Esercito Longobardo (De Bello 12, 1991) reckons that there are some Lombard graves that contain lamellae behind the nape of the deceased's neck, but no helmet. From this he deduces perished leather helmets with iron lamellar aventail. That's all I can think of. I don't think there is any mention of leather body-armour in that book.
The articles on the Lombards make several statements that one would like to see a source for!
Roy