According to the various sources here and elsewhere I can find, the following is inappropriate:
"When carrying knives however, it is best not to run."
and should instead be:
"When carrying knives, however, it is best not to run."
Yet, I find myself in normal speech often using the first form, and I wonder a) if it really is incorrect in this context, and b) why it is deemed incorrect.
The same intended meaning could also be achieved with: "However, when carrying knives, it is best not to run."
edit: yes this is a similar question to Should there always be a comma after "therefore","However" etc.? , which has helpful answers. If someone wants to close this question, fine, to me this is a more specific question though.