blackguard command undead clarification

[Soranar]

the text says :as would a cleric of 2 level lower

here's my problem. Is that ability based on his blackguard level or his character level? (cause a lot of blackguard abilities, notably the fiendish servant, are based on character level).

If it's the second option, blackguards are far more powerful than I thought

[Zilzmaer]

On the other hand, Aura of Evil specifically calls out class level, then adds it to cleric level. So, to answer your question: yes, it is based on one of those. Probably. You should ask your DM, or if you are the DM, decide which provides a level of power with which you are more comfortable.

[Urpriest]

By default, class abilities are based on class level.