Haha that was a lucky draw indeed. I never got two unique swords in a day, always some other day 😄. The first unique sword that I got was Lightning sword too as you have and completed the whole lightning set (5 pieces) in about 4 months.
Next I got was Berserker then Inferno, Dark and Blizzard. The only thing I didn't complete was the 15 legendary swords.
And about your question why there's only 6 options available in your dark armor is maybe there was some bug or glitch in the item. Resetting the options may correct the listed number of options that is supposed to be there in the 1st place.