Haki is, unironically based off of real life "powers".
Conqueror's is charisma. Dictators/leaders, people who can manipulate/lead large groups of people wield this. People like Martin Luther King Jr can use this charisma to create great, beautiful change, while people like Hitler can use it to destroy entire nations. The ability to move the hearts of others is very dangerous indeed.
Observation is clairvoyance. "Predicting the future" is really just paying enough attention to reality, IMO. Look up Laplace's Demon, then Leadbeater (well, here's a link:
https://archive.org/details/occultchemistryc00besa ). Clairvoyance is real, but incredibly difficult to pull off. It's very hard to naturally tap into that flow. You ever see someone act just before tragedy happened, or watch a sports team run a play so well, it looks like they were reading each other's minds? Yeah.
https://www.psychologytoday.com/us/blog/sense-time/201707/the-matrix-effect-when-time-slows-down The human brain/body has a lot of top-end features, we just treat our bodies like such shit (IE, dumb adults brainwash kids into being hateful freaks and feed them awful food and stick them in chairs all day long) we don't get to see many of them. Being able to slow down time near death is more or less CoO to me.
Armament is fighting through channeling energy/with adrenaline. Speed is weight. Weight is force. Force is energy. All combat revolves around displacing energy in order to form force. Mastering Armament is simply mastering the displacement of energy: (
https://dojolifehq.com/can-a-martial-artist-really-break-bricks/) you can see this in martial arts masters who have such great energy control they can chop through bricks. (
https://www.psychologytoday.com/us/...011/yes-you-really-can-lift-car-trapped-child) same thing with people lifting cars off of others due to adrenaline.
Haki is real, it's just not as flashy in real life (I'm not saying you can go Super Saiyan if you shout hard enough). Haki/Ki is about balancing your body and mind (Armament/Observation) so your spirit (Supreme King) is in harmony. I have a lot of love for One Piece, it's a very spiritually healing series. Oda's sense of philosophy is very fun to analyze and think about. Lots of Taoist sensibilities.