This spell created an exact duplicate of any bladed weapon that the caster had touched or seen wielded by another. This spell worked for creating both magical and mundane weapons. When the spell ended the created weapon dissipated and the caster could never use double steel to create that particular weapon again. Any being using a double steel blade instantly knew of any enchantments, and how to use them, upon touching the weapon.
If wielded by the caster, the blade would instantly vanish if the caster attempted to cast another spell while holding the weapon. Anyone wielding a double steel weapon did so as if they were a skilled warrior. Additionally, if wielded by the caster, the weapon could be wielded with the skill of whoever used the weapon when the caster first viewed it. This was a very useful perk if a master swordsman was observed by the caster using that particular weapon.