Improvised weapons can best be explained as objects one has on hand. These may not be designed for the purpose of personal defense but, in the moment, can be used in this capacity. When a firearm can’t be deployed or a threat doesn’t demand lethal force, an improvised weapon can be a lifesaver.
I just mentioned this in another post.
Objects at hand;
Gas pump, if an aggressor threatens you at a gas station, merely pointing the gas nozzle at them should deter them.
Also at gas stations, the windshield washer stick… just the smell of that stinky water may deter some. 
A tightly rolled roll of quarters or dimes. These balled in your fist will help prevent fist crumple and at the same time add some weight to your strike. This should by you some time to escape. When we travel where a sidearm is not legal, I’ve always got my trusty roll of Washington’s in my pocket.
Chainsaw, I once was attempted to be assaulted while I was actually using a chainsaw. All I did was hold the chainsaw in front of me in a normal hold of the saw, non-threatening- way, and the aggressor stopped and just looked at me , the saw, at me, the saw, cussed me out and walked away.
Beehive, I had a firearms student tell me once, prior to getting their LTC, that someone tried to assault her while she was trying to add a super to her bee box. After telling the person to leave her alone multiple times, all she did was shake the bee box vigorously , within seconds the aggressor (former boyfriend) was on the run. (This incident is what prompted her to take my LTC class and get her license to carry.
As a mechanic, I have a whole collection of tools to repurpose. From rubber mallets to crowbars to extremely long screw drivers. If the person does not get the hint, the blow torch will get them to see the light.
I am allergic to bee stings and carry wasp and hornet killer behind my driver seat. Although it is a federal offense to use it “for other than it’s intended purpose “, in a life or death emergency it may save my life.