Chalk line training knife for martial arts

Some people use markers and white t-shirts for knife sparring or drills in martial arts classes to see if they got "hit". I came up with the idea to use a chalk line like used in construction to mark each other with less permanence. I designed this knife as per some suggestions from one of my Krav Maga instructors- shorter blade to represent the typical everyday carry knife you might see on the street instead of the giant 8" rubber knives we currently train with. I put a blunt tip on it so stabs wouldn't hurt as much and the chalk would show up better.

This is an initial version and I haven't really used it in training yet, so I'm open to suggestions. Or just remix it.

Assembly instructions
Run a chalk like through both holes, put the line in the slot on the blade and tie them tight against the handle.
Rub a little chalk into the string and keep in sheath.
Note that marking chalk comes in permanence levels ranging from dust-off (https://www.amazon.com/Tools-STRAIT-LINE-Dust-Off-Marking-4935426/dp/B004V4KLCI/) to "permanent staining" (https://www.amazon.com/Straight-Line-Staining-Chalk-Permanent/dp/B00QZENQWE). I went with one level above dust off (https://www.amazon.com/IRWIN-64801ZR-4-oz-Chalk/dp/B00004YOC4) and it seems to be fine, but please let me know how the other levels work in the comments.

Print Instructions
No support needed, but inner & outer brim recommended to improve bed adhesion to print sheath.
Use lots of perimeters, top & bottom layers, and decent infill (I used 20% gyroid) for strength.
I used PET-G, and the bit of flex helps the sheath stay on in my bag and not crack, but lots of filaments could work. A hard TPU would probably be especially good.