I don't think its particularly fair that scouts and guides gave up sheath knives and sailors are cautious about rope cutters being left in a bag or attached to a life jacket stored, but religious groups seem to have the right to carry knives without good reason.
People get prosecuted regularly for having a knife left in a bag or in the boot, that was there for good reason, but is no longer there for good reason. I'd personally like it a bit more balanced. The burden of proof for the good reason defence is also on the accused, and that doesn't fit well innocent until proven guilty.
I would personally prefer a divers knife in my life jacket to a rope cutter, as its much more efficient to use. However, if I left it in the boot of my car and my G/f got pulled over - she'd have no lawful reason for having it. If you don't know its there you can't have a good reason for carrying it.
Yet hundreds of people are killed or attacked with knives, so its hard to find the balance. Bad people will find a way.