I agree with that. I don’t make any of my self defense practice totally rely on the person wearing any one type of outfit. My point is simply that if you’re going to attempt to grab someone’s knife arm, that’s wearing say a hoodie, jacket etc controlling the arm is much easier if you’re able to secure the sleeve. I’ve done this many times in practice and it’s amazing the control you can have. And we aren’t talking “controlled” practice either. Balls to the walls trying to kill each other. You’re able to break the persons posture, rotate the arm away from your body and honestly protect yourself while setting up to throw punches of your own. If there’s a chance someone will be wearing longer sleeves (and there’s probably roughly a 50% chance depending where you live) I’d want to train any possible defense available to me.
If you wouldn’t want to try it I understand, personally being in that close to someone trying to kill me with a knife isn’t something I want to do but I love being as prepared as I can be in general.
I’d seriously encourage you to try it if you haven’t. Have someone slap a gi , hoodie (I’ve used cotton and the firmer materials both for variety) give them a training knife and see if they can stab or cut you. I have found that the stretchier material makes it harder to break your grip as well however it has more give obviously so you need to wind it up tight in your fingers.
You need an outside sleeve grip, rotate to the outside where your palm is facing away from the attacker. This helps prevent the wrist flicking and cutting your hand. Basically keeping both of your arms pointing perpendicular to the floor as best you can and any attacks he attempts can be diverted away while keeping downward pressure.
If you know anything about controlling posture in a clinch , keeping your hips back and have decent foot work it’s pretty easy to control the attacker.