A friend of mine bought an MP-40 submachine gun from a British antique store. He then moved to Australia and tried to take the gun with him. Australian customs wouldn't let the gun in, because even though it was deactivated by the British authorities, the British way of deactivating a weapon is designed to be "reversible in times of civil emergency" so what he actually had was a fully functional firearm. And if you know gun laws in Australia, you know that you need one hell of a permit to own a fully automatic weapon. He ended up selling it back to the same antique store that he bought it from. He still has his SS knife though, that was legal to bring in.
I don't have any WWII weapons. Or any weapons at all actually, unless you count kitchen knives. I do however have Nazi-era coins and stuff passed to me through my family, who lived in Berlin through the entirety of the war before coming to Australia.