I'm going to quote what you said earlier. Maybe I'm not understanding your meaning:
I don't think he thought his kiss - the kiss itself - could kill, but Christine would die from shock, which would be a reaction to his kiss, but not from the kiss itself. The same would work for any other kind of contact. So, he was not talking about his kiss, but about Christine who was so steady.
I understand your meaning when you say that Erik didn't think his kiss could kill, but instead Christine would die from shock as a reaction to the kiss.
However, you then went on to say "the same would work for any other kind of contact".
He's already had all kinds of physical contact with her, holding her while they were on Cesar, making her scratch him, leading her into his house, taking her for walks, touching her when he chloroformed her. She did not act terrified. She mentions the smell of death, probably from the chloroform and mentions his hands are cold and bony.
So when you say the same would work for any other kind of contact, what do you mean?