DO NOT, I repeat DO NOT train with real knives that have sheaths on them, Ive seen that fail horribley.
I suspect anyone daft enough to need that advice is too daft to heed it. EDIT: I'm a big fan of this site: www.takknife.com
I know a BB who was testing for his second or third degree BB, well they couldnt find the training knofe soooo.... Yea they used a real K-Bar and figured it was ok because they had a sheath on it. And since it was a BB test they were going hard and you know what happened at that point. Trip to emergency room a few stitches and a potentially life threating injury.::Alien: The same guy had like three ribs cracked by the same instructor during a routine hip toss btw...I guess ya just had to be there right.
If it was then that story needs to go into the Zack thread: http://www.martialartsplanet.com/forums/showthread.php?t=123209 We will not have Bujingodai's thread derailed. Now, about those training knives MAP denizens....
I really like the sharkee knives, and some of them come with a "marking edge" if you want to chalk your blades. You can do the same thing with the standard models if you use lipstick or something similar. I also like these knives, but I don't know how they work as a marking knife. http://noktrainingknives.webs.com/apps/webstore/
I use Nok knives, and you can chalk them so they leave fairly decent marks. I also have Nok machetes, but they're a bit weighty for hard contact...
The site I linked has Sharkee and Bogner training blades. (I haven't seen the Bogner ones elsewhere, though I daresay they're out there). In addition to the polycarbonate(?) training blades, two of which I've got.
Nok Knives have quickly become the go to knife for experts wanting a great training tool. [ame="https://www.youtube.com/watch?v=iko5m9qTerM"]Nok Hard Contant Training Knives - YouTube[/ame]