The Skyforge Steel page say's you can craft Skyforge Steel after completing the companion's Guild quest's. PS. I know Ancient nord Weapon's can be crafted, I'll ask a staff member to confirm other detail's.
@Aurora Estrella, what is the source you mentioned regarding Skyforge Steel can't be forged ?
I only played the Vanilla version, Only Nord Hero and Ancient Nord items can be crafted only from the Skyforge. Eorlund Gray-Mane is the only person who can craft Skyforge Steel Weapons, and Wolf Armor.
Haha, you missed the joke. Both the Regular and Enhanced are crafted using steel, and following your logic on steel bows, there should be, just a joke and observation.
Actually... Crossbows are of Dwemer origin, even the enhanced steel one, which means by logic that the regular is also dwemer. Since the NPC in dawnguard gives you the quests to get the blueprints, it means that only you and her know they exist, meaning that no one else could have worked on a skyforge steel version.
What you said is actually a type of fallacy: "an item that is not made out of steel doesn't exist as skyforge steel" doesn't mean "an item made of steel exists as skyforge steel". All steel armor items are proof of this, arrows too, maces, etc.