King, unlike BM, Kizaru etc. seems to be mainly a swordsman aka gis sword is not am accessory to his power but without a doubt his strongest asset. He is referred as a swordsman, we have seen him in the flashback using a sword when he battled Oden and the scabbards. Now imo Oda was teasing making King go after Sanji and kicking him, tease that disappeared for hype in the next panels when he chocked and stabbed/smashed Sanji against a building.
Now this "fight" started very very bad for Sanji and a lot of things suggest a certain someone could just step him to save him. Said this Oda is already shitting enough on Sanji for making him use the RS as his power up (it was a gift on a silver plate from a man he has all the reasons to hate) if now he also makes him forget his rule about the hands Oda can directly made him beat Nami and Robin in the next chap at that point..
Anyway for sure when he will be stronger than King he will be able to beat him sword style or not