Hi @Chood,
Sorry I'm a bit late on this, but the formatting of the post made it unreadable on my phone, so it had to wait for the weekend when I had time to copy it to Word and have a proper read.
I’m going to steal the format my wife uses when she writes manuscript appraisals...
Firtly, this is one person’s opinion. I am not an author, editor or publisher, but I have dabbled in the industry and have been exposed to many fledgling writers of varying abilities. I am also a fantasy fan - George RR Martin, Joe Abercrombie, Stephen Donaldson, Terry Pratchett, etc. That's my excuse for what follows.

I'm going to be harsh, so let's start with the good stuff...
Chapter 1, paragraph 4. I love the way we go slow-motion until the head falls off - it's a fabulous image.
You've got a complex world built already, by the looks of chapters 2 & 3, so I'm looking forward to exploring it.
Your hero and bad guy are both subject to introspection. That makes them interesting and allows us to empathise with them, even if we don't like them (I'm assuming Osscov is good and Korxan is bad? At least for now). I want to know more about them because of this.

Now I'm going to pull out bits that made me hesitate as I read - took me out of the narrative and made me think about the writing, rather than the story. Feel free to call me every name under the sun as you read this.

Other than the map (I like maps), I thought the introduction was unnecessary. It's part of your world-building, but anything the reader needs to know should appear in the book when it's needed.
I agree with your re-ordering of the scenes, but I'd suggest your opening line should be "What was odd about this death, Osscov reflected..." (Ch. 1; par. 2) as then you're opening with a question, so the reader will at least stay to learn the answer to the question.
The problem with the scene re-ordering is it's confusing. I don't know where I am, beyond standing behind Osscov and looking at the person he's just killed. Day or night? Inside or outside? Flat ground or a hill? Raining? Field or city? How many people are in the scene? All of that could be sketched in in one sentence and then filled in as you go.
Some of the sentences seem over-written, or with an uncertain point of view. "… the blade passing through it with seemingly no resistance whatsoever" (Ch. 1; par. 1) - If we're in Osscov's head then he either felt resistance or didn't. "Seemingly" would be from the POV of a watching character. There are a number of places where you do a similar thing - putting in unnecessary adverbs that weaken the strength of the sentence.
Your word usage is clunky a times. That sentence at the start of par 2 starts so well and then uses 'blow' twice. You also use 'abnormally' and 'recipient'. I've barely met Osscov, but given he can behead a man(?) with a single blow, does his vocabulary stretch to four-syllable words?
Are heartbeats really thrumming if you're able to count them (Ch.1 par 3)?
I'm pretty sure that 'efforting' isn't a word (Chap. 3; par 6)?
I'll ignore typos except to mention that Osscov becomes Osccov after a while.
One other thing about chapter one - the title: Canvet isn’t mentioned in the chapter text, nor is a christening. Now, I know it’s where they are, but still no christening so far.

Chapter two is a massive and confusing info-dump of a thing that happened elsewhere to people we don't know or care about as yet. You could make us care by showing us the bad stuff as it happens, or introduce the detail down the line as your narrative characters find out about it.
What's the threat that forces this reaction?
How did Korxan's staff and family react to the decision? Were they part of the decision-making process?
Did he really have no choice?

Chapter three is slightly different. There's essential information about how Osscov arrived and came to be killing someone, but it's mixed up in a history lesson and still doesn't give a clear idea of why he's doing what he is.
Do we need to know the history of the island right now?
If so, how does it relate to this attack?
If no-one was expecting an attack, why were there so many guards hanging around to be killed?
(Unnecessary aside: Terry Pratchett's "Guards, Guards" has a lot to say about characters who appear in a narrative just to be killed by the hero, as does the first "Austin Powers" film.)
Note that until the end of chapter three it's not really clear if Osscov is attacking or defending the place he's in.

At this point you've probably barred me from your Steem feed and down-voted all of my posts. I get that. But I can assure you that I enjoyed what I read. I want to know why what happened in these chapters had to happen and what it leads to.

More power to your sword-arm and I hope we'll get some more chapters soon!

Hockney