KMST 1.2.440 - Kaiser (1)

I hope it's a knuckle-like weapon. More likely dual knuckles.

Considering it's placed as a low level weapon, it seems more like a low level version of this type of weapon:

 Dragon-arm Girl-thing

Which doesn't seem like it'll act much like a Knuckle at all, but more like a cannon as others have pointed out already. You can't even see the fist in there, and the ''jaws'' stick out too much for it to be a Knuckle-like weapon, and the pictures only show one being wielded and not two.