How do you get dual swords on monster hunter 1?

Hello!First of all, you cannot get very powerful duals sWords. They cannot block, and are made for very quick attacks. They can be upgraded for elements, but you would need powerful wyvern parts like Rathalos or Plesioth.

Second, you cannot just make dual sWords. You have to upgrade a sWord and shield weapon into it. Go to gamefaq and look up Monster Hunter. Go to the bottom of the page and find the charts section. Go to the sWord part and click. A chart will come up, and from there you will find out. Good Luck!