It happens sometimes. Vergo didn't use his bamboo until he fought Smoker, after Sanji and Law- although that was a much shorter arc, so there wasn't as much of a time gap. Kaku used ship tools instead of swords in W7, but they were reasonably close to swords. Then there's Big Mom, who didn't use Napoleon until after the Tea Party, which was fifty/sixty odd chapters into the arc?
Hell, in the space of a few chapters Ulti went from fighting with head butts to fighting with a mace.
With Zoans it's when they go hybrid that they are going really serious. That's when King will bring out the swordsmanship. There's a reason that we haven't seen any of Kaido and Calamities hybrid forms yet, it's saving the best til the end. King's swordsmanship is following the same pattern.
Hell, in the space of a few chapters Ulti went from fighting with head butts to fighting with a mace.
With Zoans it's when they go hybrid that they are going really serious. That's when King will bring out the swordsmanship. There's a reason that we haven't seen any of Kaido and Calamities hybrid forms yet, it's saving the best til the end. King's swordsmanship is following the same pattern.