Yeah, you probably don't need to give someone multiple bombs. It's supposed to be a one-size defeats-all last resort. It was more of a backup plan for Emet, it seems.
I am expecting to see other Haki Knots later on in the story. Almost definitely one at Laugh Tale. Since the One Piece Treasure is also known as "The Great "Hito-Tsunagi" Treasure". With "Hito-Tsunagi" possibly translating to "The rope linking all men". That probably means Haki Knots are a key part of whatever the One Piece Treasure is.
https://onepiece.fandom.com/wiki/One_Piece#Name
But, I think we could still see others, too. It probably wasn't just one for Emet and one at Laugh Tale. I think Joyboy could have hidden these knots in various places. There could be one at Lodestar. And there could even be one in that 3000 year old ancient lab that Lilith is exploring on Elbaph. Using another Haki Knot to get rid of Imu and the God's Knights would maybe be a bit repetitive after the way Egghead ended, but it's not impossible. Plus, that could set up Scopper telling us more about these Knots and how the Strawhats could make their own.
More on my Haki Knot thoughts over here:
https://worstgen.alwaysdata.net/for...al-the-one-piece-knot-what-we-expected.58965/
As for why we don't see it used more often. I imagine it's some sort of "ancient technique" that got lost to time. Especially since the World Government probably worked pretty hard to try and suppress any knowledge of it. Given Imu's reaction to feeling it happen the first time, I'm guessing the Marines went all "Order 66" on anyone who used to be able to use this technique, back in the past.
It's possible that Haki Knots could even give us a message down the line. As a reference to Quipu knot-writing from Peru. Which was used kind of like a abacus, but may have also been used to record stories. Knots as a early form of writing. One of these Haki Knots could give us the Void Century flashback we've been waiting for. A story told through knots!
https://brasaperuvian.com/blogs/news/peruvian-rope-quipu-ancient-knotted-chronicles
https://www.peruforless.com/blog/quipu
Oh, and one more crazy thought.
Remember the "Continent Pullers" like Oars? (Chapter 470) Well...what do you think they pulled those continents WITH?
ROPE! They MUST have used rope! Of some kind. And that rope would have almost HAVE to have been Haki-enhanced, just to withstand the strain of moving islands around.
And the interesting thing is...we might still be using that "rope" to this very day. Because we know that the different islands of the Grand Line are still linked together, in a way. The Log Poses allow people to follow magnetic "lines" that connect the different islands together, allowing them to navigate the Grand Line.
https://onepiece.fandom.com/wiki/Log_Pose
(Chapter 105)
Could these magnetic routes be caused by "ropes" that still connect all these islands, under the sea? "Ropes" that allowed Continent Pullers to pull these islands into place? Like Egyptians pulling giant stone blocks with ropes to build the pyramids? Either literal ropes connecting island to island, or magnetic fields that still act like "ropes" of their own. Could all Log Poses basically be following the routes of these old "ropes" that were originally used to build the Grand Line as we know it, today?
The island of the Grand Line effectively acting like a giant Shimenawa rope that wraps around the entire world? Sealing something in the core of the world itself? Like how you might use a Shimenawa rope to seal a demon into a object?
https://en.wikipedia.org/wiki/Shimenawa
https://burialsandbeyond.com/2022/10/15/1000-year-old-boulder-demon-released/
Those theories about the Grand Line being the One Piece Treasure may not have been so far off. In a way. The entire Grand Line could potentially be the largest Haki Knot ever!
Or maybe each island has their own Haki Knot at the core of the island, just waiting to be set off. Maybe the islands formed AROUND the rope, not the other way around. Kind of like how you can make salt crystals form around a piece of string.
https://www.learning4kids.net/2012/10/05/how-to-make-hanging-crystals/
That could be one way to expel Imu from the World. Setting off Haki Knots that lie in wait at the core of every island in the Grand Line all at once. You just need to reach Laugh Tale in order to "pull the string" in order to untie them all at once!
Plus...notice the similarity between the magnetic routes of the Grand Line and the Quipu knot-writing? The Islands are the "knots" and the magnetic fields are the "string", and they all converge together at the same point. Coincidence?! I think (K)NOT! The entire Grand Line...LITERALLY as the story of the history of the World! As the Haki Knot Bombs go off around the World, we could learn a bit more about the history of the Void Century, at the same time! Every "bomb" giving us another piece of the story as it explodes! Giving us a literally "explosive" ending!
...Maybe. We'll see. I'll admit, this one might be a little out there. But, I could see Oda doing something along these lines.
