Joey,
The idea that occurred to me as I thought about your post was - NOPS. Notice it, Own it, Play with it, Stay with it.
I wouldn't try to fight the image - forcing yourself to think of other things. Rather, give it your attention - watch it. In your visualizations - try to take your focus deeper into what you are seeing. Go into the knives and understand what they mean to you. You say you "don't feel myself get cut or pain.", but what do you feel? Are these knives real or symbolic? What do they mean to you?
When I meditate and project love to another person I don't imagine them so much physically - such as in hugging them. I feel the warmth of love in my heart, but it is also very focused and projected from my head and seemingly from a place outside and above my body. I feel our being and consciousness together, but I don't imagine any physical interaction. That just how I imagine the process. I think it is very valid for you to investigate how you imagine the process, just keep a positive attitude and NOPS.
Best wishes,
Blake
