Can you please tell me if putting out the havdalah flame by covering it with tin foil or a glass plate would avoid the issue of blowing out candles? Also, can you please tell me how to understand why we don’t blow out a flame? (Although Ner Hashem Nishmas Adam, I’m not sure why blowing it out is any better than extinguishing the flame through other means)
Rabbi Yosef Chaim of Baghdad, author of Ben Ish Chai writes that a person endangers his life by blowing out a flame with his breath. I assume that it comes from Kabalah. Covering the flame with tin foil or a glass plate would definitely avoid the issue.
Ben Ish Chai Year 2 Pinchos 18, Kaf Hachaim Y:D 116:115.