Personally I think 1 one handed legendaries should take half the supplies of 2 handed ones.
Alternatively 1 handed weapons should come with an account bound, statless skin that could be used on your secondary weapon.
One of my personal goals is to make a legendary, its going to take me forever and to do so and I will feel quite accomplished once I do. After all that work I would still have a secondary weapon that looks dull and be expected to do all that work again. Few players will ever get a legendary and what % of them would have 2?
I doubt they would make the cost less because it would anger those who already made them, but if a legendary skin showed up in their mailboxes I bet they would be ecstatic about it.
Yak’s Bend Zakaru [ONE]