HOW DO YOU ACTIVELY DEFEND YOURSELF IN A KNIFE ATTACK?

I used to be a cop in the United States. I would recommend wielding a pocket knife or atleast a kitchen knife at all times as long as it is legal. Go ahead and grab a hold of the attackers hand. As you have it, show him your tomodachi knife but only use it if neccesary. You can read a review on it on here

Always keep a vigil towards the knife and attempt to hold his knife hand quickly