I think Russia allows "gas pistols" with a special license too. Nonetheless, a pistol like firearm in general is difficult to aim and use.
Mace is fully legal in the US, but not very efficient.
Actual tasers (those carried by police) are probably illegal in most countries as technically it's a short range grenade launcher (it uses an explosive charge). They are incredibly useful, but are unfortunately overused in cases where they are completely unwarranted. A simplified taser-like weapon would be more useful in this cases (little training, used by someone who is statistically likely to be opposed to firearms in general).
There are different kinds of pepper (OC) spray, too.
In general Mace kind of sucks, but OC spray is an adequate untrained-person defensive choice, and OC stream or OC foam can be used in a fairly targeted way and is useful -- maybe a carbine-length OC foam dispenser would make sense, combined with geolocator, 3000 lumen 5-minute flashlight, radio communications direct to the police, etc.
