I believe the movie might have been black and white. So might have been from the 50s. It was in English and pretty sure it was made in USA.
Some alien entity/force/device/figure simultaneously visits 6-7 people scattered around the world, and gives them a small device. Similar to a ladies make up compact. Opening the lid reveals some buttons(?) and tells them how to use it. The people were geographically equally distant from each other. (i.e. 1 in Africa, South America, Australia, Europe, Russia, China, USA, and Hawaii.) And I believe all the Governments were also informed. (Or somehow very quickly found out.)
The devices, when used, will wipe out all human?/animal? life within a 1000-2000(?) mile radius. So using all 7 will wipe out virtually all life on Earth. (I 'think' it would only effect human life)
The person in either Africa or China was a woman(?) who died of illness or suicide, not long after receiving the device, (Minutes? Hours?) and her device deactivated or destroyed its internals when she died.
The governments quickly rounded up the holders of the devices, and had been told, or found out, that ONLY the receivers of the devices could use them.
I recall that either the Australians, or the USA using its 2nd device, (the one from Hawaii) took it out to the middle of the Pacific far from anywhere and had the receiver activate the device, to test its effects, watching the test from remote cameras with condemned prisoners?/animals? on boats at increasing ranges to check the range of effect, which turned out to be as reported. I don't remember if the receiver's were immune from the device, or if they had been given to people with known terminal illness who would not care if they died early painlessly.
I don't remember the conclusion of the movie. OR it may have ended with a psychological cliff hanger, with everyone waiting around wondering if someone was going to start using them., or if the governments would get together and solve their differences.
(I seem to recall quite a few movies at that time, especially sci-fi types, ending that way. i.e. one ended showing 2 stacks of newspapers at the printing press ready for distribution, one headline reading more or less, It Worked! World Saved!, and the other, It Failed! World Doomed! with the publishers waiting to hear which they should distribute.)