The Skyforge has unique smithing properties. After the quest http://www.uesp.net/wiki/Skyrim:Glory_of_the_Dead has been completed, speaking to http://www.uesp.net/wiki/Skyrim:Eorlund_Gray-Mane will cause him to describe the forge as being more "awake". Ancient Nord weaponry and armor is now available for smithing at this forge only. Weapons are listed under the http://www.uesp.net/wiki/Skyrim:Draugr category, while armor is listed under the Daedric category. These are equal to Skyforge Steel weapons in damage, but weigh less. The player needs the Steel Smithing perk to create them. Once crafted, they can be improved like normal weapons, and receive full benefits from the Steel Smithing perk, except for the Nord Hero Bow (most likely a bug).

I have heard of a glitch with the mask and robes.

Regarding crafting Daedric weapons, you have the daedric smithing perk, click on a daedric armor or weapon to craft, and it creates an ancient nord item instead? Or are you just seeing ancient nord armor in the Daedric category? Being able to craft that doesn't mean you can craft daedric armor and weapons.