I just want explain a few things regarding Sanguinus's psychic powers.
As you all know each of the Primarch has their own distinct quarks. Like Konrad's future sight, Angron's rage, Magnus's psychic powers...
As for Sanguinus's power I think he's more of an all rounder, he was supposed to be the charismatic leader to lead the charge.
Horus is more of a diplomat and 'preferred' using diplomacy (before he has fallen) of course sometimes it's unavoidable that there would be some bashing and he would do it swiftly. his special power is... super actor? Like when talking to a veteran he wound adopt a harsh worn out voice or when he's talking to his friends he would be like 'hay buddy'. Like the water cast from the Tau.
Now looking all the special perks of the Primarchs you could see that Sanguinus's has them, but more tune dawn.
Sanguinus's has the blood thirst which is remarkably like Angron's rage only Sanguinus's got it under control and he's not pissy all the time. Konrad's future sight, Sanguinus also has a future sight but less intense and didn't drive him crazy.
Sanguinius is approachable like Horus (before he fall)
He is also very positive (duh the brightest one) like Guilliman the idealists, who wanted the Space Marines to be scholars and legislators. Not as extreme as that though.
Now I'm not saying he's supper OP with powers of every Primarch but more of a jack of all trades, master of none.
—-story start—-
Sanguinius looks at the city trying to determine the level of sophistication.
After a brief glance he came to the conclusion that this planet just recently passed its feudal age. If the lack of hive structure and the lack of pollution is anything to go by.
If course there's only so much he could tell from a brief glance from a distance, so he'll need to get closer to investigate.
Naturally he can't just go walking in there butt naked so first he'll have to find some clothes.
Fortunately at the out skirts of the city there seems to be a tiny community living in boxy type of vehicles of some sort (trailer) , If those wheels is more than just decoration.
'Nomadic customs?' He curiously thought
Anyway they have clothes hanging by the sides and they seem very much unattended.
Sanguinus goes over there and examines the clothes.
'Hmm... crude' He thought as he examines a pair of jeans. Unfortunately there's no shoes
After a while he picks up a few pieces of clothes to his liking and puts them on.
After that seeing as the owners still aren't around he goes inside the trailer to look around to see if it'll give him any clues on the current situation of this world.
At the door he discovered a pair of dusty old shoes, although visibly worn and it gives out a smell but still good enough to be used.
Sanguinus frowns but nonetheless puts them on anyway.
He continues to look around but found little of use, the only thing he found that seems useful is an old newspaper laying around.
The newspapers seems old and the letters started to fade but it's still visible enough to determine the individual characters.
The language is none that he recognise, but given time and more samples, he's sure that he'll be able to learn the language.
As he was examining the newspaper he hears chatter from the distance.
'Better leave this place' He thought as he exited the trailer swiftly and heads back into a forest. He back tracked his way back to a cave he had found earlier, where he decided it to be his temporary lodging.
Now it might seem hard to analyse a foreign language.
It is but not as hard as you might think, you see all languages follow certain patterns. See the pattern and you solve the language.
One of such patterns is the Zipf's Law.
Zipf's law states that given a large sample of words used, the frequency of the any word is inversely proportional to its rank in the frequency table.
Meaning that the 2nd most often used word will appear 1/2 as often as the most used, the 3rd will appear 1/3... so on and so forth.
It's interesting how math can be used to describe languages.
Although he still has no idea what the words mean or how they're pronounced, but he can compare it to high gothic, as this planet's language is in all likelihood originated from high gothic, the common language used during the golden age of mankind.
Now with Zipf's law it helped him narrow dawn the meaning of the word but that only provided him with vague guesses further investigation is required.
Meaning that he has to go into to the city , but of course Sanguinius is somewhat hesitant to just walks into the city.
He would be like an he would be like a giant pink elephant in the room, with his wings sticking out.
He after all doesn't know how they'll react to him, Sanguinius remembers that during his childhood when he was first found by the Folk of Pure Blood in Baal Secundus. He was almost killed for being mistaken for a mutant.
Now this planet is civilised and at the peak of their development period. This planet is also not the fragmented piece of a once glorious civilisation fill with mutants.
He has to very careful.
Sanguinius thought for a few moments before deciding to to head to the city at night. He could probably stay at the alleys and observe the local populace.
He waited till night fall until he he sneakily enters the city with out much notice. While his infiltration skills might not be on par with some of his brother but it serves well enough to get pass regular human.
With his super humans senses he tries to hears and make sense of random conversations the inhabitants make when they happens to come by.
Needless to say it will take awhile but being a Primarch with his super human intelligence and add to the fact that he has just finished cataloging this world's language with Zipf's law, the duration has been shortened considerably.
After a few days
He has enough knowledge on the language to do basic interactions. From that he had gathered that this world seems more liberal when it comes to handing out information.
Probably due to the governing system of this world being an electorate democracy. It might have some good sides but it also has some fatal flaws.
It's slow and sometimes conflicted response to react to any threat, has proven to lead the dawn fall of civilisations.
Case being
A bunch of aliens suddenly shows up and started converting people
'Maybe they just want to say hello?' A dumb politician said
'A military is needed to deal with these aliens ' a general
'I'm sure there's a misunderstanding somewhere let's try to talk to them first' the dumn politician replied as the aliens converts more of the population.
'I don't like the way you address them as aliens, they're people too' another dumb ass politician steps in and detracts the topic and even more people get converted.
After a long serious debate before a response is made. And when there's a response like sending out the military to deal with it and casualties starts to come in. There will always be a bunch of people publicly saying that 'I was not for the war, we could have solved this peacefully'
Meanwhile if this were to happen on an authoritarian world
A bunch Xenos shows up and starts converting people.
The only thing the ruler of the planet has to say is 'Nuke Em'
Problem solve.
Anyway everyone basically has a device on them that has access to the world's information. This device takes on many form and names, sometimes it's called a 'Computor', sometimes a 'phoone' and sometimes a 'laptap'.
Sanguinius scours the abit before he found a drunk man dropped his phone after he called for a pick up.
The man walks out of the alley to what he presumes the area where his pick up will arrive.
Seeing the phone on the ground Sanguinius flew dawn and picks it up before retreating back to his cave to investigate the device.
—-story end—-
By the way how big is the emperor? I remember quite clearly that he was on earth since ancient Mesopotamia guiding mankind from behind the scenes. He's 4 meters big... so how does that work? Not to mention how does he step through doors? Or fit in a building half his size? Did he like crawl into buildings while using his psychic powers to make everyone think it's normal.
How does he even have sex? Then again If a baby which is hundreds of times bigger than a normal man's penis can come out, then it would be fine.