Before I moved to NZ I coppered in SE England. There, as here, the police can speak to whoever they want, and of course no one is obliged to answer... But someone walking around in the early hours who is evasive might just tick the "reasonable grounds to suspect" box and get arrested. Of course there are some utter plonkers who get the police a bad name. I explained it like this to my Dad... Just keep in the back of your mind he might have had a really bad day and the last call he was at he was having to have a fight, even at 7 in the morning. You spend your entire life dealing with violence and confrontation that if someone greets you with a smile and a pleasant attitude it makes your day and you do your best to make the most of that encounter.
As far as weapons, knives etc you have to be reasonable. When I was on ARVs we dealt with some guys who were setting up tarps etc wearing camo gear.... But the bit that caught our notice were the rifles, which later turned out to be air soft guns, which you had to handle to know they were replicas. A good way to get the wrong sort of attention. Nice boys, I remember, but could have ended badly.
As far as knives etc goes, same test. Police see some bad stuff involving knives. No idea how many stabbings a I have seen, but I remember my first one, arterial spurting, blood feeling warm under my rubber gloves. Second stabbing in my probation, the guy got it in the chest, missed all the vital organs. The offender was still there, covered in red and I nicked him. I am not "bragging" as most coppers have similar experiences, but these were just two incidents 18 years ago, and every year since has had similar or worse incidents, several each year. That's why the police sometimes get worried about knives.
I would say most coppers would be pretty sensible about bushcraft connected sharps, and the fact that most experiences with the police have been good probably underlines that. I have read posts where people seem to take enough steel to fill the Tower of London, and that always makes me wonder. A lot of people have long and heated posts about EDC knives, and seem to feel there is some sort of right to carry. The law is deliberately vague about all of this, and if you feel you want to push the boundaries the law will be carried out according to process, and a court will make a decision. But there is a shed load of stress in between. A folding knife in your pocket out in the woods is one thing, the same knife in the same pocket in the pub on a Friday night is different. And if that knife is in the pocket of someone under the influence it gets much worse.
However in my experience the biggest danger in using knives out and about comes from the user. I have cut myself a few times, those nasty ones when I should have got stitches but never did in the end. Murphy comes to play whenever you least want him, so the best advice I can give is always carry a kick **** FAK together with any sharp out in the field!