The whole problem with the “Juggernaut like Arthas” motif is… it works for Arthas.
No one else.
Arthas gets away with moving at the speed of a trundling slasher flick villain because by comparison, we’re all dumb teenagers in high heels and no inhibitions. He makes the absolute paragons of both factions look like nothing. When you’re talking a power discrepancy like that, the whole “slow, menacing” vibe works. Yeah, you might be able to outrun Arthas, but that’s all you can hope to do. You can’t kite him to death, you can’t zip around and humiliate him, you can’t snipe him from a distance - all you can do is run and pray.
Problem is, you can’t have that kind of discrepancy in a game where classes are supposed to be more or less equal. Sure, someone’s on top, and the situation will shuffle the deck somewhat, but you can’t have someone running at 50% speed and 2500% capacity in all other areas. The “Run from the unstoppable killing machine” vibe can’t fit into that model.
The Death Knights can’t be implacable destruction because there’s a bare minimum placcability built into the fundamental concept of the game. Balance won’t have it. You have to be a minimum level of vulnerable, and the “horror villain” vibe can’t withstand that fact.
Also, the “dual wielding” image is on its face all about speed and agility - striking fast and as many times as possible. That’s the whole idea on the face of it. Thus, that too flies in the face of the Death Knight as this lumbering, slow moving brute. It doesn’t work.
Blizzard’s described what they want and what they’re going for with the Death Knight, but none of that changes the fact that it’s wholly untenable. Even at the utmost of extremes, if they pushed it as hard and fast as it can go, that “Arthas” vibe cannot be achieved. Not in a fair setting on a fair playing field. In the end, their weapon set says speed, while their mobility is ponderous, and their overall capacity is lacking on all fronts. Death Knights aren’t Inevitable Doom Incarnate - they’re an asthmatic goth mall ninja waddling out of a buffet.
Drop the “I wanna be Arthas” schtick - it’ll never pan out. Bring their mobility up to par, and redesign them to be as fun and functional as the game space will allow.