Im starting to think the "power of love" is related to haki tho. See, the two things Sanji used to beat Queen after he destroyed the suit: Insane Color of Observation, Armament Haki in his Exoskeleton, and flames (which we still have no explanation about where do they come from), the sole fact that Sanji wasn't take over by the Awakening (but managed to revert back to normal like his eyebrows) alongside all the other stuff, that is a big deal.
Sanji has mentioned this kind of power many others times in the past, like it made him stronger (for the most part it's related to protecting Nami or just protecting something he likes)
Haki is all about willpower as well. Sanji also mentioned he could protect his body with CoA to protect himself, against Black Maria for example, but the way he lets S-Shark hit him freely is too much of a flex.
Also, this supports my theory of Sanji being able to control his genetics (turn in "on" and "off" for instance) without changing his personality through Haki (Conqueror's specifically). So Conqueror's could not just be potentially a boost to attack power (through CoC coating) but also something that Sanji can use to increase the strength of his "Devil Fruit" (with DF i mean the lineage factor modifications, that Sanji went through just like someone who eats a Devil Fruit). Pretty similar how Luffy does with the Nika Nika no Mi, his Haki has always been important to create new Gears and make his powers more unique, and i see that Oda is making this to be the case on Sanji's case as well..
I think that is what Oda meant with the Warrior of Liberation and the Warrior of Science. The meaning of Warrior goes way beyond of the meaning of mere fighter, its like the more human part of the combatant, who makes mistakes and learns through them, that has dreams and ambitions and things they wanna protect with their life.
The "Liberation/Science" part is basically tied with the stuff that Luffy and Sanji never asked to be, it just happened to them without they previous consent and approval, they were gifted with something that could comfortably be more of a huge curse than actual gift if we look at the grand scheme of things.
I think Oda is just waiting for the appropriate moment for Sanji to realize that this is the case (waiting to reintroduce Sanji's ambition to find the All Blue as well). That is why Sanji fighting an actual King from the North Blue is such a fitting idea
Chef Zeff already made that clear to us tho. Im waiting for these panels come back someday, Zeff is so important to Sanji and Oda has to deliver it fr.