Taking a liberty away is taking a liberty away!
A possible use for self defense is not too important. Beer, cars, planes, can all kill people when they are used without responsiblity, yet they are not banned.
Banning things never works. Regulation works. Maybe never 100%, as there is no way to stop people from being responsible 100% of the time.
Guns are no issue here, as simply very very very few people are interested in having guns, so it might not be fair to draw a parallel.
Gun laws allow almost any type of handgun here. I just googled for Dutch gun shops, and this gives a fine overview on what can be purchased legally here:
http://www.slendebroek.serverthuis.nl/html/geweren.html
Yet, you DO need a permit from the police. And every gun transaction is registered.
I think it's not too hard: A government can decide where, when, how, howmuch quite easily.
The same applies to drugs: Government decides what kind of drugs are legal and local government decides who can trade/retail it.