A great thread to explore
I always suggest dictating manifestations. For example I say, “Appear to me & speak with me in a way I understand, and is comforting and familiar to me.”
They do like to make you feel at ease. So just saying “appear before me” or “show yourself” is like so random you’ll never know what you’ll get. So I’d suggest more dictation in your evocations.
I too have seen Belial as a pit fiend as mentioned but also as a beautiful man. They are immortals and have infinite forms, so while we’ll see similarities unless you’re I a ritual space with another magician, it will vary from person to person. And as mentioned the energy never lies so you will get used to each entities personal energy.
Karma