The Master variant Tekkai, or Iron Body is the "Titanium Armor" technique is straightforward - it makes the defense stronger by turning iron into titanium. However, The technique comes with a drawback, The user is also unable to move while activating the technique making it a risky move to use. Even if it were as strong as a diamond, He would not use it. Armament Haki is a much better option.
Shigan, or Finger Pistol has a Master variant "The Palm Shotgun". This technique shares similarities with the Hyuga clan's technique, but the key difference is that it can be utilized as a long-range attack by simply aiming with the palm. Palm shotgun disables the flow of blood and this technique has an effect similar to being hit by a shotgun blast. This is a powerful move that is not easy to master.
Majima aimed at a group of seabirds flying nearby and decided to test his skills on them. He concentrated the energy from his body onto the palm of his right hand and launched it forward using his Shigan: Palm Shotgun. The resulting air bomb traveled in a large arc towards the birds, and one of the closest birds felt a sense of danger and froze. However, to its surprise, the air wave suddenly changed direction, causing the birds behind it to crash into the sea. The birds were shocked and realized that Majima was like a devil.
The seabirds quickly flew away as their strong low warning sonar spread.
Majima looked at his right palm in amazement and exclaimed: "This is amazing!"
The technique's ability to hit accurately even without a clear line of sight is truly terrifying.
The rumors were not exaggerated at all.
In addition to mastering Rokushiki, he has also achieved mastery in Haki.
The basic forms/ techniques of observation haki are:
Presence Sensing
Observation Haki users can feel and see the presence of others around them or even people who are far away easily. For example, Fujitora, who is completely blind, was able to sense the presence of people around him back in the Dressrosa arc.
Intent Sensing
Another basic form of observation haki enables the user to predict and sense the intent of another person. Now, this doesn't mean they can foresee the future, This ability helps the user in battles as they can pay close attention to how the adversary moves in order to foresee their assaults and evade them. For example, Luffy was able to dodge the attacks of pacifists after his haki training with Rayleigh.
Strength Sensing
Additionally, the user can also sense the power and strength of the people around them without even fighting or anything. The user can detect the powerful aura of a person and estimate their strength and even the haki they possess.
Emotion Sensing
Emotion Sensing enables the user to perceive other people's emotions and understand how they are feeling within their hearts. This allows the user to perceive others' presence and experience their emotions over a massive area. For example, Queen Otohime could sense and understand the people's feelings in the Fishman island arc.
Future Sight
For a brief period of time, the person can predict/ foresee the future using this advanced observation haki. It's useful during battles as the user can predict the attacks and counter them.
The Voice of All Things
Only a handful of individuals possess the ability to hear the voices of sea kings, Zunesha, and even objects like Poneglyphs. For example, in anime episode 567, Luffy was able to hear the voices of the sea kings on Fishman island, just like Roger was able to. Currently, we only know that Luffy, Roger, Oden, and Momonosuke are the ones who can use this unique technique.
Majima has reached the master level of Observation Haki, which allows him to see a few seconds into the future, Majima's Variant is Future Sight it is the same as demonstrated in the original story.
Armament Haki has its subtypes, although it is significantly more diverse:
Armament Haki Subtype 1: Invisible Armor: The invisible armor type of Haki is a manifestation of the Armament aura around the user. It can be used to attack the opponents, or defend against blows.
Armament Haki Subtype 2: Hardening: Possibly the most common Haki type, hardening is a black layer of Haki that constructs on top of the part it is used upon. It can be used by most characters in the New World, especially those who possess decent strength. Just like any other Haki, the proficiency a person has on it varies, and so does its strength.
Armament Haki Subtype 3: Byogou: Used by Charlotte Katakuri, this type of Armament Haki seems to be the succeeding degree that comes after Hardening. Busoshoku: Byogou (Armament: Defence) was extensively used by the Sweet Commander against Luffy and every time they clashed, it proved to be superior to Luffy's Haki.
Armament Haki Subtype 4: Emission or Ryuo: Ryuo is what the people of Wano have named this spiritual ability. In essence, Ryuuou is similar to regular Haki, more or less. The only biggest difference that has been observed between the two is that while Hardening is a coating on the skin, Ryuuou is more of a flowing technique in which Haki blasts out from a distance.
Armament Haki Subtype 4: Internal Destruction (Advanced Ryuo): Advanced Ryuuou is a far more refined type of Armament Haki which, instead of damaging from the outside, seeps into the body of the target and destroys it from the inside out.
These abilities become master-level as one's Armament Haki cultivation progresses. Emission or Ryuo, which can penetrate the surface and directly damage the inside of an object.
Like the other two haki types, Conqueror's haki also has a few advanced forms:
Conqueror's coating or Infusion:
Similar to armament haki, users can imbue conqueror's haki into physical attacks and weaponry for a more powerful attack. This technique can be combined with armament haki as well. But, only a few people are capable of using this technique like Luffy, Kaido, Roger, Whitebeard, and a few others. For example, In episode 966, Roger and Whitebeard clash against each other by infusing their haki into their weapons.
Observation Killing
This advanced form of conqueror's haki allows the user to stop their opponents from using observation haki by unsettling them with their overpowered haki first. So far, only Shanks has been able to use this technique.
Majima's Variant is Conqueror's coating or Infusion.
When this powerful Haki is condensed and wrapped around a hand or weapon, the energy is concentrated in a fixed position, resulting in unimaginable power.
With his current mastery of Conqueror's Haki and the Rokushiki, he can potentially outmatch any powerhouse in the Pirate World.
Unless he encounters a Devil Fruit with unique abilities, Majima can move around as freely as Kaido, even more so!