Braided cables tend to be somewhat more damage resistant than the regular rubber sheath thats used in cables (and looks snappier). There's absolutely no other advantage to them other than that.It won't fray, its less likely to break if it gets caught in something, and if it does fray or got cut, hopefully it would just be the outer layer.I'd note in that specific keyboard, the cable is also bolted down to the base, AND glued, so its very definately quite durable.
There is no 'performance' advantage claimed, or is there any.It will not reduce noise, or reduce latency, or cause world peace. Its just cable with nicer clothes.
I do have the fancier version of the blackwidow, and its a rather nice bit of kit (i got the one with the backlight, and USB/headphone passthrough), and its a rather comfortable microswitch keyboard (which is why i bought it) , but it hasn't made me any better a gamer!