No 1 do not keep in a rucksack.
No 2 be aware of your surroundings, if your wearing headphones change to a single ear piece.
If you've a rucksack you could line it with a bit of board or similar to act as a stab resistant board.
Don't think about a knife no 1 probably end up in the poop no 2 you need to train with a knife.
Expect to get cut, celox, tourniquet and an Israeli bandage in a small 1st aid kit,that is easily accessible and know how to use it.
If ever it happened the blade is the priority but use extreme violence it will happen in seconds.
We train knife survival it is luck of the draw anyone selling knife defence is full of s**t.
A decent torch with strobe and serrated toothed bezel is handy for seeing at night! Again know how many times to press the button!
These are possibly legal along with deodorant or similar