Hands, tusks with possible appendages and a trunk swinging the last one.
Those sickles of his look weird, considering his size. I imagine, if he were a swordsman, he'd have a more imposing weapon. And those sickles didn't have anything memorable about them. It's like they're more of a tool and less a dedicated fighting style, similar to BB's guns, for example.
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For an arc this big, on a Swordsman Island, I doubt Zoro will have just one serious clash.
Just hope Sanji can make enough sandwiches in time.
I mean Pica wasnt really a swordsman either but he had a sword. There has been foreshadowing in colour spreads in the past of zoro vs mammoth.