I read up on it, since nobody else answered.
It seems that the Swedish knife laws prohibit any kind of knife in a public place, unless you have justifiable reason.
Now, I am not sure how this law is practiced, but it is an almost carbon copy of the Norwegian knife law, and I can answer as to how Norwegian law is practiced.
In Norway, if you carry a knife to work (e.g. carpenter) it's fine. If you carry a knife camping in the woods (or on your way to the woods), it's fine. If you carry a knife as part of a traditional folk costume, it's fine. If you carry a knife on a Saturday night in a dance club, it is definitely NOT fine.
When they passed the law in the early 90s, they included the clause about "honorable cause" (work, camping, etc), and specifically said that the law was not intended to restrict Swiss Army Knives and small pocket knives.
Now, fast forward to 2004.
Norwegian police arrest a taxi driver for peeling an apple in a public park, with a 7" fixed blade.
During an ILLEGAL random public search, police find a Leatherman's Tool in a businessman's suitcase; confiscate the tool, and fine him.
Long story short, and assuming Swedish law is practiced like Norwegian law:
- If you want to be entirely certain, you don't carry any kind of blade.
- If you are a well-behaved and well-dressed person, the risk of getting into trouble is probably minimal. I carry all the time.
- If you are a backpacking tourist, pretty much any size knife should be OK, as long as it is in your backpack.
- It also seems that in Sweden, "rapidly deploying" knives such as automatics, are illegal to have if you're under 21, and illegal to sell in any instance. This I'm unsure about, but I definitely wouldn't choose to carry an Emerson Wave....
Hopefully a Swede will come along and give you a bit better insight.