I know for a fact that sometimes Harpers will wand people. They have their usual door staff but sometimes they have contract security as well. I have seen these contracted security staff wand people at harpers. They are Wizard Security and have the bright yellow security shirts that have the wizard on the front. While they may look like rough customers, most of the people who work for Wizard are generally mello and very nice, and usually respectful. They are typically better than anyone who works for the Lyons Group in my opinion anyway.
However, they may or may not be able to find your CCW/knife/kubotan/whatever and they may or may not know how to handle you if they find it.
If you have any problems; politley ask to speak to Jeff, he's an older guy with long hair and a moustache- he is the head of Wizard. He's a generally nice guy, I have no idea if he is pro RKBA or not, and if the management at Harpers tell him no guns even with a license, I'm willing to bet he'll tell you the same.
All in all though in my travels to Harper's the Harpers staff and Wizard staff have been pretty chill and I've never known them to be the "kick your ass" manhandler type staff of some other Boston area clubs.