I think about it more and more, but it makes me wonder:
"Could the greenblade have actually been a prototype of the greensteel design?"
Granted, the Greenblade has powers that ordinary greensteel cannot contain, but with the design of the weapon, and not to mention, if I am correct, it was in existance before the Vale of Twilight was released, could this have been a attempt by someone to create a replica of the powerful Greensteel design?