Looking to forge a blade? Let me explain the process...
Obviously, to forge a dual weapon you need two swords as base materials. The two swords must be common, basic, bound or masterwork items.
Generally speaking, swords of the same type must be used, common with common, and so on. However, a masterwork sword combines with a common sword to forge a dual weapon. Masterwork items exist for B-grade or better, as I'm sure you're aware.
I suppose I should tell you that I can only combine swords of the same grade, otherwise the balance is thrown off and the blade becomes unwieldy. Also, keep in mind that any enchantment you've placed on the blade will be erased when it is combined.
I can combine weapons up to C-grade. For anything higher, you'll have to find a bigger city and someone with better tools than me.
Lastly, you should know that you can't combine weapons that have been bestowed with other skills, unfortunately it just isn't possible.
Right, now that we got the boring stuff out of the way how about we talk business.