Darius is incredibly weak and inefficient at what hes doing.

He can't tank for days without having all of his items be tank except 1 damage and even then he isn't very tanky. But having 2 more base armor makes him the tankiest champion in game without items according to boards.

His ult doesn't do that much damage without 1-2 AD items and even then that risks being less tanky meaning never going to have a chance to ult. But his ult is the most overpowered ult in the game according to boards because it does true damage.

Darius's kit is incredibly poor, either has slug fests with melees(he's arguably the best slug fest melee duelist in game), or he gets kited to death by a ranged hoping to have a chance to even grab them and even if he does, lel ranged champs have flash like Darius too so flash pulling isn't an option and it's not like most ranged have a dash or 2 in their kits. But according to boards if you can pull somebody he can 100-0 anybody within 2 seconds.