What weapon would be best for fighting against robots?

First Human VS. Robot Fight in History (FULL LENGTH)
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Found this over on ZeroHedge, wherein I also found this line:

The machine wasn't fighting on its own: a human handler was controlling it, according to Futurism.

Magnus Robot Fighter

This got me to thinking and I posted this over on reddit:

What weapon would be best for fighting against robots? 

This is speculative, but people are making ever more capable humanoid robots. I think some are even operating out in the public, giving people directions, stuff like that. But they are getting better everyday and it won't be too long before police departments all over are going to be wanting some robots for directing traffic or hostage negotiations or who knows what.

Anytime there is power there is potential for abuse, so what kind of weapon do you want to have when a humanoid robot is breaking down your front door?

Once upon a time there was a comic book called Magnus - Robot Fighter. Magnus had been trained up to disable robots by punching them with his deadly Magnus punch. At the time (many years ago) I thought that was pretty fanciful. Back then, any kind of machine was made of steel and was stout. Punch that sewing machine all you like, it ain't gonna break. But then we got Star Wars and the armies of marching humanoid robots and I thought, you know, Magnus could probably handle these guys because they were made by the cheapest bidder out of the lightest materials (weight matters when you are being transported by starship). One good punch and they would crumple. But weight won't matter so much for Earthbound robots. And you can bet that robots being sent into harm's way are going to be armored.

I suppose the first question we want to answer is just what kind of armor are attack robots going to be wearing? And if it's super tough, maybe we want to attack it electrically like with a beam of microwaves or possible ultrasound? Guess we would need to experiment to see just what would work. Or course, the old armored bulldozer trick would work, but you're liable to end up with more damage than just your front door. Though, in extreme circumstances, it might be well worth it.

Magnus has appeared here before.