Aside from its miasma, which was very familiar with Zombie Lords, they could also tell that this creature was a Zombie Lord because of its special attire.
It wasn't wearing a nobleman's attire like the Zombie Kings, but it was equipped with various mystical items protecting its body…
Well, according to what they were aware of, the Zombie Lords were guards of Sofia.
From the various information that Shane had gathered, Sofia was the only one who did not turn into a zombie after being injected with the Project Z's failed serum, which turned out later on to be the Zombie Virus.
Instead, she showed remarkable resistance to the infection and even developed some enhanced abilities, such as increased strength, speed, and healing.
She was dubbed "Patient Zero", the key to finding a cure for the zombie virus.
In any case, the guards of Sofia, for some reason, had mutated to such a level… They were the ones who had become Zombie Lords.