When SHs faced a Villain (Crocodile) who took away other's Water, We witnessed Water Luffy
When SHs faced a Villain (Enel) who took away other's Gold, We witnessed Gold Luffy,
When SHs faced a Villain (Foxy) who took away other's Nakama, We witnessed Afro Luffy,
At this point, it kinda hit me that these Situational Luffy Forms are kinda based on his Crew,
Water Luffy references Jinbe, Gold Luffy references Nami, Afro Luffy references Brook,
It continued then, with Moria stealing Shadows & We witnessed Shadow (Nightmare) Luffy,
And in that Form, He became a Monster whose Design resembles Chopper's Zoan Form,
We also had another Situational Form when Villain was someone who took away other's Food,
Tankman was basically Food Luffy, and it's a Reference to Sanji,
My point is,
We are currently against a Villain who instead of collecting Food, Shadows, Gold, Nakama ... etc
He collects "Swords"!!
It's obvious which Situational Form Luffy gonna show soon,
Luffy will temporarily get a Sword Power-Up, and if it happens in Elbaph, then only Swords available are Harald's Sword stuck in Jarul's Head and Massive Sword next to Adam Tree, but judging from previous Arcs, I believe Luffy will take over one of Imu's Blades,
Actually...
Since Nika had both a Sword & a Spear, and Zoro/Sanji are now fighting such Weapons given by Imu,
Then most likely Scenario is that Luffy gonna be able to compete against Imu by acquiring that Sword & Spear after Zoro/Sanji win their Duels,