I think it's ellegal to have a locking blade. Small pen knives, multi tools and things like that are fine. If your in a workshop, on building site or out camping, it will likely be overlooked, but if you're found with a knife in your pocket in a bar or in a town centre, you will likely get in trouble for that.
In the UK our strict laws regarding knives and firearms go back to way before 9/11. Shotguns and hunting rifles are allowed, but you need a permit and there are other restrictions on how they are stored; firing pins removed, stored in locked cabinets, stuff like that. I think firearms must be single shot too, so no multi round magazines, automatic pistols, assult rifles, that sort of thing, but I'm no expert.
If you look at the number of deaths and injury's involving guns and knives there's a stark contrast between the UK and US and I for one would rather not allow any old nutcase, with a questionable political ideology, buy an assault rifle.