I predict by the end of the series we will have variations of the three core types of haki. Simply because the way chinjao forshadowed it as being the determining factor for this part of the grandline. The same way being DF user was a major boost in The first half is the same way having major haki skills will be the deciding factor in the New world.
- CoA
- Only hardening the tip of something turning into a blade like cutting haki
- Hardening the air around you as like a shield. Black and physically holdable
- Hardening the air around you into projectiles like little black bullets
- Hardening water or liquids into any shape you want.
- Hardening everything in the room into one solid block making movement for anyone but you impossible.
- CoO
- Sight base observation that allows you to see insanely far.
- Predictive Based observation that allows you to see shortly ahead into the future
- Surrounding based observation that tells you about every non living thing around you.
- Temporal Based Observation. Having your observation being so good your brain speeds up and time seems to slow down (which humans can do Irl when in extreme danger. Altering our perception of time is quite easy)
- CoC
- Controlling the Weather around you
- Controlling people around you
- Infusing with attack so each blow confuses your opponents will making it easier to KO them
- Convincing people that you are their captain and to do what you say.
- Jedi Mind trick. These are not the Devil Fruits you are looking for.