What this mean is that it is HIGHLY unlikely we’re gonna get a training montage of Sanji learning something like Advanced Armament like we did with Luffy. We’re not gonna see him actively training to learn new skills and techniques (unless they involve cooking) like we do with Zoro. Almost every power and ability Sanji possesses has come to him naturally. So stop trying to compare his power development to Luffy’s and Zoro’s.
What happened to Sanji in 1028 makes perfect sense for what Oda has done with him in regards to previous power-ups and it doesn’t hurt his character arc in the slightest.
People tend to diminish Sanji for his fighting feats but just forget the matchups he has been put in. Before the timeskip he always fought one of the strongest men from the enemy crew alongside Luffy and Zoro. The thing started to change after the timeskip, when he didn’t get much focus “battlewise” and was put to fight crazy strong people like Doflamingo and Vergo(who was being very hard for even Law + Smoker to deal with).
It was only in Wano that Oda started to show Sanji’s actual potential, putting him against enemies closer to his level and, ultimately, against his strongest enemy up until now: Queen.
He’ll come out of this fight as a Second Yonko Commander tier, just a little bit less strong than Zoro, because he HAS to. Damn, he’ll be one of the Wings of the Pirate King, guys.