I keep all my dwellers un-armed, and arm them when it's needed. This way all my best weapons are available at any moment. After an incident, then I need to un-arm all the dwellers I previously armed. I can't find a good way to do this; is there some way to see an overview of dwellers and their weapons? Or some way to ensure that all dwellers are dis-armed?
Your best bet: Keep your best weapons on people on the uppermost floors, just for raider attacks. If you don't have anyone on the top floor (I have a Vault Door Room and expanded Living Quarters, rarely populated) then you can drag people up from the floor below; keep them armed with the best.
When a localized incident occurs (fires, radroaches), the game should zoom in on the incident room. Simply arm all the people in that room with the best left-over weapons, and as soon as they jump for joy, immediately disarm them. There should only be six of them at any given time so it should never get too out of hand... Assuming you don't send around people with better stats/clothing (I've never seen any reason to do that).
This is assuming that you have people in every room. For otherwise unstaffed rooms, you're going to have to import all of the people from somewhere else. In that case, it is best to drag people over from another room on the same floor, so they don't have to contend with waiting for the elevator. Because of this, try to keep at least one fully staffed expanded room on each floor. So long as they make it there quickly, the incident should not spread; and if they're all coming from the same place, it should be relatively easy to disarm them afterward.
Unfortunately there is no absolute way of mass viewing each dwellers' attire and weapon as of yet. I've taken to following the same plan of action as well. But I've found that the easiest method is to just keep tabs on who you've equipped and find them in the dweller list by tapping the gear in the corner of the screen after the incident has been resolved.
An alternate plan of action could be to have a designated team of people with high skill and good gear that can be sent around to resolve incidents - just to prevent having to equip and un-equip various dwellers constantly.