First up, let me clear one misconception:
The Murasame as a unique weapon does not exist.
Instead it is a nickname given to a certain weapon which meets a certain requirement.
This is the biggest secret in the mod, and if you don't want the fun spoiled to you, close this window RIGHT. NOW.
You want it, you have it.
There ya friggin' go.
How I got it? Overrefining.
And i'll show you how to get this in 7 steps.
1. The proper sword.
As it is there, The Horseman's Blade is the sword that you'll want to use. The reason why it's a Horseman's will be explained later. So just get one. BUT. You have to make sure it is on a prefix with a tier smaller than Legendary. If the prefix is in the same tier as Legendary, this will not work. If you're confused on what i mean by this, i'll give you an example with a Blood Butcherer. It's tier 1(blue), and if you reforge it with a good prefix, it goes to tier 2 (green). If you reforge with an even better prefix, you will get tier 3 (orange). Examples of 2 tier increasing items are Murderous, Savage, Godly, and of course, Legendary. If we were to do this with a Blood Butcherer, we would want a tier that's 2 or lower. The higher the tier, the better, but it can't be the same tier as Legendary. So do this, and let's get refining.
2. The Blacksmith.
I am only including this as a step because i'm sure many people didn't do it, so i'll help you with that. The Blacksmith only comes on singleplayer, so be aware of that. As for requirements, you need either a Gold or Platinum Bar in your inventory and a free house. The Blacksmith will then come. Once the message saying he came appears, look around your spawn, as he will be standing there. Usually inside the ground by 1 or 2 blocks, but you can still use him. He can take a while to come, but patience is a virtue. I've too had a bad time trying to get blacksmith, since he took a lot of time to come. But eventually, you'll get him.
Before doing this, please take note that you will need a lot and a lot and a lot and a lot of money. It's preferable to have several chests filled with platinum coins around you for the next steps, so a merchant is ideal. To get these coins, you can either keep farming for days by hand, or, the smart choice: Use an auto-clicker. It saves you lots of time, and it's what i normally use to stockpile all these platinum coins.
Right click the Blacksmith, and click the Refine option. You'll be brought to a menu similar to that of the Goblin Tinkerer's reforge. You refine the sword. It costs a lot of money to do it, keep that in mind. You'll notice that +1, +2, +3 and so on appear at the end of the item, and that it goes up to +10. When it reaches +10, if you refine it again, it will lose it's +, but it will go to the next tier (Ex: for the blood butcherer example, it was tier 2, it would then go to tier 3). Normally on vanilla the last tier is Tier 9 (turquoise) but if you reach Tier 9 +10 with this and refine, the name of the sword will be written in red. This is a new tier (Tier 10) on NTerraria exclusively for highly refined things, and it's the highest tier. And that's why we want to make it an even HIGHER tier, by reforging it to a better prefix.
This is the part where the lack of a Legendary tier prefix is important. Because you would increase your tier by reforging from something into Legendary, but since you're already at the maximum tier, it rolls over and becomes white. Pro Tip: If you're not on a really good computer, the game might freeze for about 10 seconds before rolling onto a white tier prefix. This can make the reforging tedious, but with enough luck you'll get it. You can also settle for Ruthless if you want more damage.
Overrefining is the act of refining something while it's in a rolled over white tier, which you made your Horseman's into on the previous step.
However overrefining is bugged, and because of the bugged tier that rolled over, you can refine it infinitely, since nor the game or the mod programmed a limit into it. Though the cost exponential growth is programmed, so that's where the chests of platinum coins will come in. You just now gotta select the Horseman's, and spam the ever living crap out of the refine button, using up all your money. If you run out of money on your inventory, just grab money from the chests and keep refining. This will make your sword stronger and stronger and stronger and stronger and stronger.
For it to be considered a Murasame, it needs at least 200k shown damage. As you see in the image above, mine is 302k. Usually 2 inventories of Platinum Coins is enough to accomplish that damage on maxed out titans. Of course, you can refine it more if you want. The speed, damage, knockback, and most things increase with the refinement, and you'll see your sword get extremely fast and powerful.
Now that you have overrefined it to the point of almost breaking your finger (or autoclicker, i won't judge you), congratulations! You just got yourself an awesome murasame, the slicing machine that will strike fear into the most brave bosses' hearts!
Go mock your friends about it and pwn everything!
Let me answer some questions that are probably going over your mind.
Why a Horseman's Blade? A Terra Blade has higher base damage and shoots Terra Beams!
Well, this deserves quite a lot of explanation. First up: Weapon breaking. When swords are refined too much and with too much speed, they will plain out stop shooting projectiles. If the weapon has a prefix, you can see it's speed modifier. The Terra Blade breaks at around +80 to 70% speed. But even that would render Terra Blade better than Horseman's, since it has more damage. But, the Horseman's is bigger and also has pumpkins. The pumpkins aren't counted as coming OUT of the sword. They are summoned from hitting an enemy, kinda like if you hit someone wearing a star cloak. But instead of stars, they summon pumpkins that home in on you and damage you. A lot. Also, i don't even need to mention that a pumpkin does almost twice the damage of the sword. That makes the terra blade seem like a joke.
Why a sword? Let's make a 300k damage Sniper Rifle!
Weapon Breaking applies to almost everything. In fact, the only thing safe from it are swords and flails. Pickaxes aren't, magic weapons aren't, summons aren't, nothing. Not even rifles. Once they get to a certain speed, they become too fast to swing or fire.
How does this happen?
And by that you are probably refering to the fact that overrefining is a thing. I have no idea either, but just the idea of the tiers rolling over can give you a pretty good example. Make the answer for yourself.
So, as i said, overrefining is infinite. Meaning i can definitively not the one with the strongest Murasame by the time you're reading this. No one knows who is the one. And more mysteries come in with the solve of one. Yes, i did spoil a huuuge secret. But one day in the future, someone was going to have to do it, and i might as well cut whoever person that is' job.
I relogged, but i can't refine it anymore! Help!
Yeah. That is one problem with overrefining. Relogging. If you relog with something overrefined, it's rarity will become turquoise. You'll have to change it's prefix on the tinkerer(preferably to something lower) and refine it again. You'll be able to get it to red again, so just reforge to a now better prefix to get the white tier and you can just keep overrefining again.
Can we make Murasames out of ranged, magic, and summon weapons, by refining them just until almost the point they break?
That isn't a new thing, in fact, i and many other people have been doing this since the murasame was first discovered. I made 3 other murasames so far. A ranged one using a Sniper PXL300 (weapon from the mod), but it's only on a locked server world, so i don't have my best ranger to use it with. I plan on making one with the normal sniper rifle, and on a world that isn't serverlocked. My magic one isn't really super powerful, but this Razorpine has been doing good. I will experiment with different weapons later, and settle on one that might be better. The summon one is the only really stable one with a stable damage, and it's awesome on this summoner i made. I use Number Matter to get a huge ammount of Sharknados from this awesome Tempest Staff.
Flairon Murasame? Hm... Flailasame!
Already done. Not as strong as the sword version in damage but might as well be more useful, since it has the bubbles, and it does 1/3rd of the damage. I refined it to a certain speed that makes it go completely through walls except on some really specific slope/half block formation designs. I think i can fix this with more refining, but these are tests for another day. I am still experimenting with different types of murasames, trying all i can to make more, more, more.
And who knows? With the item cloning glitch in Terraria, these toys might become a little more available.
I got a weapon with a prefix named Murasame. Does this mean i got the Murasame or something? And why does it go away when i relog?
I have seen lots and lots of comments about this. Yes, there is a prefix named Murasame. It's a random chance, and it sorta acts like a second prefix. You can get, for example, a Broken Murasame Copper Pickaxe. It works even with other prefixes, and the only thing it does is double the weapon's damage. This is not the only prefix that does this. The Murasame prefix is only for melee weapons, and Ranged and Magic weapons have their own too. Ranged weapons can get the Arisaka prefix (somehow, coins and other ammo can also get it. Probably because ammo counts as ranged, and coins are ammo for the Coin Gun), which, like Murasame, doubles the damage. Magic weapons get a prefix named Compundium (correct me if i'm wrong, i have absolutely no idea how to spell it). Summons share the Compundium (again, correct me) prefix with Magic weapons. I don't really know why they go away when you relog, but they do. Just like rolled-white tiers. Goes away.
So no, you didn't get the Murasame. You just got a prefix that doubles your melee weps' damage. Yes, i've already got questions about getting a Legendary Murasame Horseman's Blade to Murasame stats, but that's for later. And by later, i mean whenever A. I want to try it, and B. I get lucky enough to get one.
Have a question? Ask it in the comments and i might answer it here!
Credits to Mohl that discovered this setup.
Credits to DarkGGG for perfecting it and also editing this article.