If he comes to an individual, beginner or otherwise, he has deemed them ready to work with him, and one should be fine. But he is a harsh teacher, and many of his lessons can be outright draconian. I would not personally recommend him to a beginner, unless he has already made himself known to the person.
He often will teach through ones dreams. The deeper one works with him the more intense the dreams can get. And as I stated above, some of his lessons can be downright horrible. Why? Because he teaches us to confront ourselves, the deepest darkest aspects of ourselves. The nightmares that result can bring you to the brink of insanityā¦ but he has the precision of an OCD rocket scientist, and will not give you more then you can handleā¦ just be warned that you can handle a LOT more then you think you can!
Ultimately this process allows you to see the world as it REALLY is rather then how we idealize it, and also to help you confront your fears. From this place one can establish a solid foundation for ones progression. Working with Asmodeus will aid EVERY aspect of your life. And if you take him as a teacher he may just decide that you need to be dragged through hell to give you perspective, though it is not guaranteed that he will do so. Everyone is different after all.
Working with him you will notice that your sense of individuality increases. You will start to despise being passive and lazy. Your ambitions will build, as you get tired of eating the shit the world feeds you. You will build self respect, self esteem and confidence. Your ability to interact with and seduce the opposite sex will become effortless, far beyond second nature.
Many of the rites in his honor do have a sadomasochistic component. One of the things he teaches is the ability to use our pain, anger and frustration as useful tools in our ascent. So the fact you saw a knife where your penis should be is no surprise. He also has the capability to teach you haw to use sexuality as a weapon. So he may have been showing you part of his nature.