You are right in that originality regard.
Thing is that Sanji did not had any long drawn out fight and first one that he will have will take place during this arc. Grill Shot was one of attacks I wanted to see used outside of water, on land but I imagine that it is kept for later for very strong enemy that can tank it being left with moderate damage. Sanji felt like slightly holding back.
As for him letting Suit pass and Okama Kenpo not - he was not pushed very hard. He was overpowered by Doflamingo who immobilized him and had dangerous clash with Vergo that was cut off after one chapter. We will see this arc what he has to offer and if he was holding back with Okama Kenpo because of his pride.
That's partly why I'm saying Oda doesn't know how to handle Sanji. Or just isn't interested in it.
Plus all the stuff people already said.
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Is newkama kenpo better then what sanji already has? He was beating NK guys like Mr 2 since alabasta, it was never somethign that was show superior.
Ivankov is like the best NK guy we ever saw and he is based on his fruit power instead.
If anything, he should learn from guys like Sai that have dragon drill kicks.
Yes but NK seem to be more similar to sanjis leg style, unlike fishman karate. And based on their team up on Wadatsumi, it didn't look like oda wanted to show jimbe's superiority over sanji. Sanji even got to finish him instead of jimbe.
Kenpo doesn't need to be "better" than what Sanji already had for Sanji to incorporate it into his moveset and do his own thing with it.