The Chorus Blade is a sword you craft in the End from parts taken off the Chorusent and the Choruslings drifting around it. It lands 7 damage at 1.4 attack speed, so it swings slower than a 
Diamond Sword does, and roughly half of its hits will leave the target with Chorus Infection. It also hops you a few blocks on right-click, which makes a handy dodge.
You won’t be able to craft one until you’ve been inside an Ancient Tower Remains, as the 
Chorus Crystal sitting at the top of the recipe only drops from the Chorusent. Everything else is an 
Iron Sword and fruit the Choruslings hand over freely, so the boss is the real gate on it.
Obtaining
Both of the mod materials come out of the same place, so the whole job is one trip to the End’s outer islands. Towers are spread thin across the world, so a locator beats flying around looking for one.
With the tower found, the order below is the one that wastes the least time. Each step feeds the next, and the boss comes last because everything else is easier with the floor clear.
Find the Tower
End Highlands or End Midlands
Ancient Tower Remains generate on the outer End islands, in End Highlands and End Midlands, about 65 chunks apart. That’s a lot of empty End to cross, so craft an 
Eye Of Chorus from four 
Chorus Fruit around an 
Ender Pearl before you set out.
Throw it and it’ll fly toward the nearest tower within about a hundred chunks of you. Like an 
Eye of Ender it usually drops back on the ground afterward for you to pick up again, so one or two will see you there.
Clear the Choruslings
One to three fruit each
Choruslings are the smaller ones around the tower, and they also spawn on their own out in End Highlands, End Midlands and Small End Islands. Every one of them drops one to three 
Infected Chorus Fruit, so two kills will normally cover the recipe. Their attacks apply Chorus Infection to you as well unless you’re blocking, so don’t wade into a group of them with your Shield down.
Beat the Chorusent
Drops the crystal, guaranteed
The Chorusent is the tall one inside the tower, with 200 health and hits of 12 to 15. It takes nothing until it stands up and teleports away from anything you throw or shoot, so it’s a melee fight, and the Chorusent page has the full breakdown. It drops a single Chorus Crystal and nothing else, so that’s one blade per boss unless you go and find another tower.
Where the Parts Drop
The craft itself is a shaped recipe on a 
Crafting Table, with the Chorus Crystal above an Iron Sword and an Infected Chorus Fruit either side of it. The Iron Sword is consumed as normal and nothing carries across, so don’t waste an enchanted one on it.
Two Choruslings will usually cover the fruit, and the crystal is a guaranteed drop, so the recipe is never the hard part. The temptation is to eat the spare fruit on the way home.
Infected Chorus Fruit restores 5 hunger, but it gives you Chorus Infection for 8 seconds every single time, with no chance roll on it. Keep the stack for crafting and repairs instead.
The 
Chorus Mask is the other thing the fruit goes into, along with a second Chorus Crystal. If you plan on wearing one into the tower, that’s a second Chorusent kill before the blade, and its recipe is on the second tab above.
Usage
In the hand it’s an ordinary sword with a slower swing, 7 damage at 1.4 attack speed where a Diamond Sword gets the same 7 at 1.6. Durability is 750, so it’s well short of Diamond, though it is fire resistant and won’t burn up if it ends up in Lava.
Chorus Blade
Iron Sword
Diamond Sword
The infection is where the rest of the damage hides. Half of your hits put Chorus Infection on whatever you struck for 3 seconds, and while it’s running there’s a small chance on every tick for 3 damage plus a short teleport, which over those 3 seconds averages about three of them.
That damage is magic, so armor takes nothing off it. The teleport is the useful half of it, as a mob that keeps getting shuffled a couple of blocks sideways loses a beat closing back in on you.
The Teleport
Right-click, sneaking or not, and you’ll be dropped at a random spot within about 5 blocks, at the same height. It needs open air to stand in and a solid block underneath, and it gives up after ten tries, so it’s dependable on open ground and does nothing in mid-air or on a narrow pillar. A failed hop only costs the 1 second cooldown.
Nothing is spent using it, there’s no durability cost and no hunger drain, so the cooldown is the only thing holding you back. It’s random rather than aimed, though, so it’s better used to break out of something’s swing than as a way to cross ground.
Enchantments
As far as the 
Enchanting Table is concerned it’s a normal sword, with an enchantability of 14, the same as Iron, so it takes levels reasonably well. Nothing on the item blocks any of the usual sword enchantments. Repairs are done with Infected Chorus Fruit on an 
Anvil, which is easy enough to keep topped up as the Choruslings never stop dropping it.
None of those change the teleport, which stays on its 1 second cooldown whatever is on the blade. Mending is the one that matters most, as fruit repairs are cheap but Anvil levels are not.
Tips
Fight on flat ground if you’re counting on the teleport, as it needs somewhere to land and fails far more often along the edges of the End islands. If you’re fighting anywhere near a drop, step back onto solid ground before you start relying on it to get you out of trouble.
Wear a Chorus Mask around the tower, as it strips Chorus Infection off you while it’s on your head and both the Choruslings and the Chorusent apply the same effect you’re about to be handing out. The catch is that it’s crafted with a Chorus Crystal of its own, so it competes with the blade for the one drop the boss gives you.
If the swing speed bothers you, the config does list a Chorus Blade multiplier and a Chorus Blade Speed multiplier, both sitting at 1.0 out of the box. Nothing in the mod actually reads either of them though, so moving them off 1.0 leaves the blade exactly as it was.
FAQ
Both land 7 damage, so the difference is in the swing, as the Chorus Blade runs at 1.4 attack speed against the Diamond Sword‘s 1.6. What you get back for that is Chorus Infection on half your hits and a teleport on right-click, neither of which a Diamond Sword has. Durability is the other gap, 750 against 1561, though Infected Chorus Fruit repairs it cheaply enough.
The teleport hunts for a spot at your current height with air to stand in and a solid block below it, and it gives up after ten tries. Hovering with an 
Elytra, standing on a single block pillar or fighting over a gap will all fail that check, and you still eat the 1 second cooldown when it does.
The blade only puts it on whatever you hit, so swinging it is safe. You can still pick the effect up from Choruslings and from the Chorusent‘s own attacks, and eating an Infected Chorus Fruit will give it to you every time, so a Chorus Mask on your head is the answer if it keeps happening.
Chorus Crystals come off the Chorusent and nowhere else, one per kill, so another one means another Ancient Tower Remains. The Eye Of Chorus keeps that quick, as it’s only four Chorus Fruit and an Ender Pearl and it usually survives the throw, and the same crystal is also wanted by the 
Chorus Cannon and the Chorus Mask.
