[quote=KabenSaal]
Maybe it would deflect a stone from a sling, but javelins and arrows deliver enough impact that it is hard to deflect them without getting hurt, with medieval technology.
[/quote]

Stab an ice pick as hard as you can against an angled piece of metal. Then use a hammer. The ice pick catches an angle and glances. The hammer smashes.

[quote]Short range, bows would not penetrate leather, more than likely.[/quote]

Law of conservation of energy. The arrow is going fastest at close range, before air resistance works on it.