Maybe there is 1 or 2 of you guys out there who don't use SMG's with laser sight 24/7 , and might have prestiged the b/knife twice.
I've had a ton of fun playin' with it on its own lately, (destroyed a dragonfire with it earlier - why, oh why theatre mode do you not work ) but I can't for love nor money, see my emblem on it.
I never knew this either...until a couple days ago. (I only have Marksman on my Ballistic Knife)
I was playing Michael Myers and was looking in third person after I died and saw the emblem on the knife you shoot.
I don't think you see it in the killcam, so pointless because you can't see it at all. But yeah, on the knife you shoot.