Although Cerulean/Cobalt blood have special eyes such as Vriska, Aranea, Mindfang, Ardata and Remele, it's weird to see that Elwurd and Mallek have ordinary eyes

I mean, it’s just like how Zebede doesn’t have psionics, or Azdaja has three horns, special Caste things are tendencies, but not things that happen all of the time.