@Pipio:
I think haki comes in three stages of effective use.
Color of Observation:
Level 1: Sensing a number of people or animals around you. Possibly a specialty in this skill could be sensing emotions and intentions.
Level 2: Sensing general movements of people and animals around you and by extension some inanimate objects.
Level 3: Master level, is perfect sensing of everything around you, and holding an unconscious level of senses slightly greater then level 2 while asleep but not as high when focusing.
The Color of The Conquerer:
Level 1: Basic form is intimidation of people or creature greatly weaker then the user but is only effective in close range and only effective against people/creatures of incredibly weak resolve. Also those who hold a special gift for this color can inspire others through direct contact.
Level 2: Effective against a wider range or people/animals with higher to top tier level of resolve. At this level the haki can produce a physical presence/force, most likely felt as a strong wind or blast of g-force. This force most likely breaks resolve of enemies of top tier resolve thus lowering their combat ability. At this level friends around this user would feel greatly inspired in times of danger and perform beyond their normal abilities. All Other humans of all resolve levels will a sense of inspiration, loyalty and respect.
Level 3: Master level, effective lets this user intimidate people/animals with mid to weak resolve unconscious at will. Unconsciously the user will inspire loyalty and strength from everyone around him expect those who also use this haki. This user presence/g-force blast would be incredibly strong enough to topple buildings, change directions of attacks, and destroy ships without lifting a finger. With proper control a user could inspire a nation over night.
Color of Armaments:
Level 1: The ability to imbue force into the users physical body at basic points of contact. eg. hands, feet. The user would be able to withstand greater pain/dmg to the body part imbued with haki.
Level 2: The user would be able to phyiscally push his haki out his body at a long distance. Effectively being able to harm devil fruit users without needing to hit them. Flying slashes from swords, elemental blasts from DF users and all attacks could be stopped at a safe distance from the users body. The user could also improve his/hers attacks with an aura around his weapon of choice protecting it from damage.
Level 3: Master level of this haki would afford the user completely control of the defense and offense of this color. Allowing them to block attacks of all types with ease and effectively break through all defenses of DF users and haki users with weaker armor. An user could live closer to the edge of death without dying instantly.
In the straw hat crew I think the haki rankings go like this: Luffy: LV2 Coc. Zoro: LV1 CoA, LV1 Coc.
This is just my imagination :D
Level 4 (above Gol D. Roger's level)
Observation: Can pinpoint location and movement of all things (living or nonliving) around person. Can predict, to extremely high accuracy, complex movements, multiple movements, and chain reactions. Can hide presence from others even in plain sight.
Armor: Haki can take form of a invisible spherical barrier around user, as well as be condensed to a smaller area. The barrier deflects all attacks, to the limit of Haki strength. Level 3 properties still apply.
Conqueror: Adding to Level 3, transforming attitudes, personalities, and nature of behavior. Halts and extinguishes attacks and ill intent toward user and allies. Even fires and explosions can be quelled instantly. Enemies with high resolve and morale lose much of their strength and resolve. Entire societies can be reformed overnight. Corrupt leaders gain compassion and rethink their ways.
Level 5 (If Jesus, as proclaimed by some Christians, was in One Piece)
Observation: In addition to Level 4 prediction and sensing, reaction times are much, much faster. The user may feel that other fighters and objects move in slow motion, some to the point of standstill. Others may feel the user's presence as a figment of imagination or an illusion, all the while getting their butt kicked.
Armor: Haki barrier can now repel objects and energy continuously over a distance, including the ground and the sea. Movement strength and speed increases due to force from Haki. Ignores Haki defenses, and physical armor. Only a stronger Haki armor can defend. Haki is stronger enough to push away (previously) anchored buildings at blinding speeds.
Conqueror: Unlocks the potential of kings within all people chosen by user (Inspires color of conqueror in people normally not possessing it). In addition to destructive capabilities, the user can use color of the conqueror to heal and repair damage, as well as trigger growth and construction. Can resurrect the dead (inspire spirit and life in corpses). Former archenemies can be made into faithful allies in an instant. User can control natural occurrences, like wind, sunlight, temperature, humidity, rain, lightning, earthquakes, volcanoes, ocean waves and currents (including parting waves), water temperature, toxic gases, radiation.
BTW, about my previous post about Whitebeard being weaker on Observation color, I meant that I see Whitebeard as being weaker on observation compared to his other Haki abilities, even though he is a master of all Haki types. Being terminally ill and aged caused his Haki to be drastically weaker than it was in the past.