No possible arguments to support dual wield over 2h?
Dont make me laugh. If you want to leave out lore, fine, but that still leaves how the spec was designed since wrath and damage output. It was designed as a DW spec and it alone held the DW talents for the death knight class. The damage output was also higher aside from 1 point in WoD where Blizzard screwed up design and balance even after they were warned.
In Wrath DW did more damage even without str weapons and hit just as hard as Blood did which was a 2h spec. Cata, DW again came out ahead in terms of damage and was the start of the end for 2h. MoP, again DW was superior and the playstyles became more split unlike in wrath where they were the same and you just picked your weapon, even if 2h had at the very least 15% less damage than DW. WoD was the death nail with the 25% downtime driving up the damage each ability had to do which when combined with the obliterate buff for 2h it was doing way too much damage and was nerfed maybe 2-3 weeks into the expansion and since that point on DW was ahead and scaled better.
The only argument for 2h is “I want to use a 2h” which again, is perfectly valid.
My argument is not just lore based, but mechanics and damage output based. In terms of mechanics, DW has an extra Runeforge, has more crit rolls due to the extra weapon and more killing machine procs. You can argue that it wasnt how it used to be, which I agree.
Ill leave you with a little fun fact too, the playstyle that you 2h supporters are so fond of, was how DW played as well. Only when they started to make the playstyle distinct from each other is when the death of 2h began. In wrath all that you had to do basically was keep your diseases up, convert blood runes to death runes, use rime procs and then pump out as much obliterates and frost strikes as you could before you had to refresh your diseases.
2h supporters are the vocal minority and for some reason they think the playstyle now is because of DW which it isnt, its because of poor development. Just look at how bad of a design Killing Machine is to see just how bad the spec is designed.