Long post:
If the fleet that kreig amassed, along with the hundreds of his weapons, armours, and even his poison gas can be seen as his might then the spear of that boy (Luffy) is his own brand of might all the same
No matter how many hundreds of weapons or armour one is equipped with, they're no match for that "one special spear" that comes from your guts.
On a battlefield of pirates where life and death is decided the one who fears death shall fall to their doom.
Perhaps it comes from his complete preparedness to survive no matter what or his conviction that fears no death.
Zeff further goes on to say he happens to know of a certain idiot aka Sanji that will stifle that spear for no good reason.
This is what Zeff said to Sanji about Sanji and Luffy.
Then you see Sanji come across the Germa and Queen who use armor and technology and weapons. So in the Kreig and Mihawk fight Sanji is questioning fighting when the odds seem against victory. Zeff mentions this. What I seem to notice is that Sanji has yet to really have this moment of reference just yet. Even though the Queen fight is a reflection of this. Zeff says Sanji seems to be dulling his spear. Oda hinting awakening something. We would guess that happened vs Queen as I said but I don't see it that way. Now recall Luffy saying guts is how he withstood Kaido. Guts was used by Zeff too in this speech set. Special spear to me, and others, would seem to be Haki and Conqueror's Haki. And I say this because it talks about weapons armor and one may assume it is just Queen that this pre-ts speech relates to since that's been the one serious fight he had. But he had the Germa. But even before that he fought Vergo? What is Vergo? A mass of steel and Haki. Something that also fits the description of Kaido and Big Mom but to an even greater extent. Haki can be considered both a weapon and armor. What did Kaido say? In the New World, Haki takes precedence over Devil Fruits. So the armor and weapons also refers to Haki users. Next part I said elsewhere in a post that Zoro said he'll become the King of Hell if he has to. Yet in contrast Sanji said he could stay as he is, or he can become a monster who could easily dispose of enemies as strong as Queen for the sake of Luffy. Basically he chose what Zoro did not. Zeff saying, Sanji is dulling his spear for no good reason. Now here is this other part. Chopper spoke on wanting to be like a human and then changed to he's willing to become a monster for Luffy. Now although no one expects Chopper to get Haoshoku Haki, it comes across to me as Zoro and Chopper chose to go all in. Sanji seems to still be riding the fence. Oda had Sanji tell Zoro to kill him if he loses control. Now that may sound like Zeff's conviction, willing to die speech but it isn't specifically. Sanji's character is still fearing turning evil. As Zeff said dulling his spear for no good reason. It seems a good reason on Sanji's part. However Sanji isn't guaranteed to turn evil. He shows faith in Zoro to kill him if comes to it but at the same time Sanji hasn't had to put himself in the position where he really has to cross over to that. Similar to Luffy telling Kaido, he'll hand Kaido and leave the rest to everyone else. Furthermore since Conqueror's Haki is the will of a King well Sanji should have the willpower to overcome this armor that could turn him evil. Meaning although he's taken a step forward, he hasn't completely.
In fact I could Sanji is like the Kenshin character. Where he had to overcome his turning into a manslayer. As Sanji was designed to be a machine for war. In relation to One Piece the Raid Suit is Sanji's version of Enma. One carried the risk of draining Haki and one carried the possible risk of removal of emotion. One would physically kill the user and one may kill the humanity of the user. As I also said, where Sanji chose to discard the Raid Suit for this reason Zoro chose to embrace it with Enma rather than throw away Enma. And I know some people will say that is proof Zoro is superior to Sanji and Sanji won't get conquer's. But my point is that I believe it shows that Sanji hasn't fully gotten to the point Zeff mentioned back then. And of course there was a reason Oda did it this way and had Sanji flashback to Luffy and Zoro. They've been described as a trio. Oda was also hinting this speech to fit Zoro as well. And as we see the Queen battle we see Luffy and Zoro have crossed over into CoC and ACoc. I would also say this situation is similar to Goku, Vegeta and Gohan in the original DBZ. And Gohan not yet achieving being Super Saiyan. Not that Sanji doing so would make him stronger than the two but that Sanji has not reached that point of conviction Zeff has referred to. Even Yamato has ACoC and Yamato had a point of conviction in her character including in her want to defeat Kaido as well. To me that says Sanji is probably going to go through one more major obstacle before that aspect of him is actually completed. As it was introduced in what separates him for Luffy and Zoro. Zeff and Oda basically says Sanji is like Luffy and Zoro but he's choosing to suppress himself. Judge even goes along the lines of saying Sanji is mentally weak. Technically, since I used DBZ and Seven Deadly sins as an example, his hells memories is a bit similar in the whole early Gohan anger thing. And when Meliodas was touchy about that half broken sword. But yeah the whole point, seems Oda linked the Baratie and these last two arcs to hint at more power ups. So again, when they mention a spear that armor and weapons are no match for well that can definitely be Haki. And Sanji's two fights showcasing Diable Jambe and Ifrit Jambe for the first time had him normally doing good damage against tough types of defenses but then powering up to bypass it internally. Now Sanji bypassing tough Haki, would be the development of ACoC. And to develop CoC would be mental and willpower thing. So at that time it will probably be when Sanji really crosses over into the whole concept of Zeff and talking about dulling spears.
Furthermore I have this wonder and, I feel it would be really hilarious where you know how Sanji told Judge that Zeff is Sanji's real father? We all find out that the reason Jusge has a mask on is because Zeff I actually secretly a Judge clone. Which makes no sense because he's listed older than Zeff. Yet at the same time it says Germa soldiers take 5 years to mature to a 20 year old. Meaning Zeff was the early prototype. And wasn't really born before Judge but aged due to the experiment. And Oda is hiding this from us. Also, if I'm correct that would likely be the reason spears were used by Kreig in Sanji's introduction arc, Zeff mentioning spears and Judge having a spear as well.
Of course someone also said Nika uses a spear so the comment hinted at Luffy and Nika. Also of course the Shandian people. And those automata characters are scientific apparently. This last part is just a random add. If it all connects to something unsure.
I'm CACKLING OMFG 
