Transcription** & **Interpretation
でも(but) with a sentence ending particle denoting assertiveness, 『さ』.
I googled the difference between もし and もしも and as far as I can tell, there’s no difference, they both mean “if”. This is followed by 腕 which we’ve established mean skill and not arm in this context. Self-confidence in the negative, 自信ない, is nestled between 〜なら and もしも, so in the case a person has no self-confidence.
執刀 means to perform an operation and なんて means ‘such as’.
So if a person has no confidence in their skill in performing operation… what I’m missing is しなきゃ. I imagine しなきゃ is する in the non-past negative but what is きゃ? Is it just a colloquial manifestation in this context?
All in all, I think it means:
“but in the that a person doesn’t have confidence in their ability, they won’t perform surgery won’t they?”
…or something along those lines.