First thing first, if they pull a weapon, for me that is an act of lethality and as such I no long hold back until you are no longer a threat (military training, plus growing up in a rough school and neighborhood).
If they are, as you call it, helicopter fighting, use defense over offense. Letting them tire themselves out is truly the best start, but the best thing I have found is stay just out of their immediate range and dodge (if your a speed fighter like me) or block (if you prefer power and can take hits, and he isn't using a blade) the first few hits, then get inside his guard and land a blow to the throat, solar plexus, and/or groin. When he is stunned, twist an arm behind him and lock it there while tossing him to the ground. Should take care of it.
Of course, if he is using a weapon, what he is using changes everything. Plus his size to yours is something to consider.