An issue with Darkweave Armor

[Amberyll]

According to the description for Darkweave armor, "tough and flexible as leather, with considerably less weight and encumbrance", it should weigh less than Leather. This is incorrect. The weight listed is exactly the same:confused:. Does anyone know what the weight listed in the sourcebook is?

[Zoberan]

also, the compendium states 5% spell failure but the actual items in agame are 20%. Why is that?