"Leather lamellar" is entirely made of leather (small leather plates joined to each other by leather lacing or other cords). Lamellar armor does not need a backing (i.e. small plates and cords are all there is), although some still have it.
(Inside of a metal lamellar armor)
Which shows that how insanely tough leather armor actually is - that piece of leather actually resisted not just glancing blows, but quite a lot of directed powerful hits.
Skall also does dane axe/wood axe and light crossbow test on the leather. It resisted all but the heaviest blows from the axes, and survived nearly all crossbow shots excepts the one with a wicked hunting broadhead tip.