Yeah, that's why we know Weevil has a DF.
It was in the volume 1000, the same who had canon information about Sengoku, Koby, etc.
Not to mention, at the time we didn't even know who Weevil was or what he looked like: we only knew that he had cut off Z's arm... and when we saw Weevil for the first time, much after the volume 1000, he did in fact had a cutting weapon as a main weapon.
It was in the volume 1000, the same who had canon information about Sengoku, Koby, etc.
Not to mention, at the time we didn't even know who Weevil was or what he looked like: we only knew that he had cut off Z's arm... and when we saw Weevil for the first time, much after the volume 1000, he did in fact had a cutting weapon as a main weapon.