Out of curiosity what would the other devil fruit be in your mind?
Because to be real, Invisibility still just does not seem that cracked to me. Garp could clearly sense Shiyru so it is not like it negates observation or anything. Even if Shiryu masters it and fully becomes "nothing" by the time he fights Zoro, it seems very much still hard countered by just using future sight since even if you cant see the attacker, you would know where it comes from etc
It might be me just being annoyed that Oda did not just give Shiryu the Diamond fruit (which I will admit would have just made him an armament training tool instead of observation) but there are clearly fruits much more dangerous in my mind that Invisibility for a "best devil fruit combo" pick. Especially for a swordsman.
Like, even just to name the fruits of the other Blackbeard pirates, I think Shiyru would be much more easily able to enhance his raw combat power via the Van Augers Warp fruit or Burgess Strong fruit than the one Oda gave him.
Legit, Oda could give Shiyru the coolest devil fruit sword he will ever make (think its probably gonna be some epic snake due to his nature and everything) and even make it mythical, that still wont make the Invisibility fruit that great in my mind.
Let's start with, even if all Shiryu has is what we saw, as bad as it was presented, it still allowed Shiryu to end the career of the legend that hunted the Pirate King. Just because Garp sensed him it didn't stop Shiryu from delivering a fatal injury. In Oda's eyes, Shiryu was the fitting one to critically injure legendary Marine hero, not the ex-Admiral Kuzan.
That being said, now we enter the theory part - Shiryu will not do the same things Absalom did with that fruit. Just like Blackbeard will not do the things Whitebeard did with Gura, he will do more with it. Sabo will not do the things Ace already did, he will do what Ace couldnt. Every DF that is re-using an old Devil Fruit serves one purpose - to do what the previous user couldn't do.
And since we haven't seen anything new from Clear no Mi, it means it is saved up for the future, for one particular fight to be precise.
You should be familiar by now what I expect from Clear no Mi's Awakening - the strongest defense in the world if you choose DFs as source of your power, superior to any mythical Zoan and what not. The strongest body is the one that doesn't have a physical form.
Regarding the other Devil Fruit, I am betting all my chips on Yamata no Orochi that has shown close to nothing on trash character like Kurozumi Orochi... When handing over the fruit, it was hinted that it was special - I will give you
power.
Yamata no Orochi basically allows Shiryu to upgrade to 8-sword style due to 8-headed sword, attacking from 8 different directions.
That is the best offensive power when the source of power are Devil Fruits.
That means that Shiryu has the best offensive and best defensive powers thanks to those Devil fruits.
The only better offense and defense than those are the ones that are sourced from Haki - that is why Mihawk is unbeatable.
And if Oda wants Shiryu to parallel Blackbeard's 3 DFs, he could even do that, give Shiryu another sword with either Zoan DF or Kizaru's light sword to parallel all 3 types... All I know is that Shiryu will be something else and nobody is ready for it.
No power ups. Yet it will be wss zoro who beats nasjuro. And zoro next arc who beats shiryu
WSS is the finale, WG war isn't.
I know you disagree on this.
But we will see this soon enough.