Weapon Twirling

It's well known that when it comes to fictional fight scenes, what looks exciting and cool is far more important than what would be effective in real life. That's where Weapon Twirling comes in, because Everything Is Better With Spinning. It's visually interesting and looks like it may be difficult to pull off, and is thus cool. It's also used when a character would otherwise be standing idly, since someone just standing around with a weapon isn't as interesting as that person doing fancy tricks with that weapon.

In some instances, spinning weapons are used to block projectiles or create wind attacks.

In fencing and sabre, spinning your sword is called a moulinet, and is used to move a parry to a circular cut, although you'll rarely see it used this way in fiction. It is also used to warm up before a match, which may be where creators got the idea.

Outside of special circumstances, however, spinning your weapon tends to leave you open to attacks, since your control of your weapon is compromised. Deconstructions and parodies will have the fancy twirling interrupted with an attack to demonstrate this.

If the weapon twirling is being used show off before an attack, probably with the intent to intimidate, it's also Intimidation Demonstration. Can also overlap with Unorthodox Sheathing.

Supertrope of Gun Twirling. Subtrope of Everything's Better with Spinning.

Anime and Manga

 * Soul Eater: Every single Meister in this series seems to love doing this. It may or may not aid with Soul Resonance or not, but it sure looks cool and eats up a few seconds of screen time.
 * In Bleach the third seat of squad 8 tries to intimidate Chad with some quick swordplay, and just gets punched in the face.
 * Just before Tousen unleashes bankai on Kenpachi, he walks forward, twirling his sword in his right hand.

Comic Books

 * The Disney comic "La cappa e la spada" has Goofy write a novel where one of the characters used to be a knight who loved to show off by twirling his swords (even lampshading that it's much more impressive than doing it with revolvers.) He stopped using physical weapons altogether after one stabbed his foot while in mid-twirl.
 * One anthology comic had a series of short stories involving a Samurai known only as "The Young Master," escorting a blind little princess about Japan on behalf of "The Great Lord" while fending off assassins (at least once, the assassins were sent by the Great Lord). The most Badass swordsmen in the stories tended to twirl their swords after fighting, with some implication that they were doing this to sling the worst of the blood off their blades, though this was never explicitly stated that I recall.

Film - Live-Action

 * Riddick does some knife-twirling in The Chronicles of Riddick.
 * In The Fellowship of the Ring, Boromir twirls his sword a few times while waiting for the goblin horde to break into Balin's Tomb in Moria.
 * The infamous scene in Raiders of the Lost Ark where a swordsman shows off and Indy just shoots him.
 * The lightsaber fighting in much of the Star Wars prequel trilogy involves lots and lots of spinning. There's at least one portion in Obi-Wan's climactic duel with Anakin that has both of them spinning for a solid 20 seconds.

Live Action TV

 * On Buffy the Vampire Slayer, Buffy would often twirl a stake for effect.
 * Whenever there are swords out on Merlin, somebody twirls one at least once.

Video Games

 * In Knights of the Old Republic, there is a "Flourish Weapon" ability mapped to a key, and can be used to spin blasters, swords, and lightsabers(!) around dangerously. Including the double-bladed lightsabers.
 * In both Super Smash Bros. and The Legend of Zelda: Twilight Princess, Link sword twirls after every major kill. In the games you can use it as a taunt.
 * Final Fantasy
 * Final Fantasy VII: Cloud does this as his victory dance.
 * Final Fantasy IX: Zidane does this when he's equipped with double-edged swords.
 * Kingdom Hearts: In the original, at the Coliseum, Sora will imitate the victory dances of Cloud and Squall, this is the result.
 * Chaos Rings II is rather fond of this trope.
 * Darwin twirls his sword before he sheathes it and before performing his  two Awakenings.
 * Orlando spins his machette-like swords after attacking.
 * Marie spins her staff after attacking and as part of her Awakenings.
 * In Fire Emblem the Sacred Stones, some characters twirl their weapon above their heads as part of their critical hit animation.
 * Yosuke from Persona 4 does this while in battle and in the opening animation. It backfires when he nearly drops his dagger in both.
 * Kid Niki: Radical Ninja has the title character attack by spinning his sword in front of him.
 * In Tales of Vesperia, Yuri weaponizes it with his Shining Fang arte, twirling his weapon to slash the enemy multiple times.

Western Animation

 * In Avatar: The Last Airbender, Aang is fond of doing this with his glider staff. Since he can use it to create wind attacks, it's also Justified.
 * Beck nearly gives away his secret identity as the Tron imposter in Tron Uprising to The Dragon by doing this with what appears to be the Grid's equivalent of a Swiss Army Knife.