Useless Accessory

"What? Oh, those are pouches?! I thought they were wearing ballet skirts. I guess whatever they need to take with them into combat they need to take a whole lot of it in single-serving sizes."

—Something Awful, on utility belts

An accessory which characters never actually use but which is noticeable enough they must consciously choose to wear it.

For example, a Discredited Trope from the Dark Age of American comic books was superhero costumes featuring a large number of pouch-covered belts and harnesses - which never actually seemed to be used.

This is a Super-Trope to the following tropes:

Compare with Chekov's Gun (not to be confused with Chekhov's Gun). Also related to Cosmetic Award and Badass Bandolier. A Full Set Bonus can make such an item a subversion.

Before adding examples, Please make make sure that they don't fit in a Sub trope.

Examples of Useless Accessory include:

Anime and Manga

Yuuno's side-pouch in Lyrical Nanoha, which we never see him use. Some Fan Web Comics (Omake (?)) have made speculations on what he places in there.
Sailor V's mask is this. Unlike Sailor Moon's similar mask in the manga it has no point aside from obscuring her face. When she becomes Sailor Venus she continues to wear it offscreen for a bit and during her introduction (probably so viewers/readers know that she and Sailor V are the same person) ditches it once she joins the team and her identity is never revealed due it.
Yoh's headphones from Shaman King. They're such an integral part of his character that seemingly every villain calls him "headphones" at one point or another, ~~but when do we actually get to see him using them?~~ but he stops using them after the first few chapters.
- Supposedly he has them in the first place to block out other people's thoughts. How headphones help avoid mind-reading is another big question. In reality they belong to his father and he stole them so he could feel closer to him.
In the Anime of the Game Sands of Destruction, Kyrie's knife is this. In the game, he dual-wielded knives, but in the anime he was turned into a Non-Action Guy and Dude in Distress. The knife remained part of his design as The Artifact, and is never used.

Comic Books

Rob Liefeld is notorious for giving all of his characters costumes with dozens of tiny pouches, including pouch belts on their thighs, which never seem to be used.
Used on-and-off by Deadpool, whose pouches are almost never used. When they are used, they have contained action figures (of himself), wallet, keys, and (on one occasion) a pancreas. Then again, he's Deadpool. Logic doesn't work on him.
Bob Burden's Flaming Carrot wears flippers all the time, in case he needs to swim.

Film

When Star Wars first came out, did anyone question why Chewbacca was wearing what looked like a clunky sash and nothing else? The Expanded Universe eventually established it was a bandolier containing various tips (explosive, armor piercing) for use with his bowcaster.

Live-Action TV

Doctor Who: The Doctor has rather Rummage Sale Reject costumes, but the fifth Doctor also wore a piece of celery in his lapel.

Tenth Doctor: (~~Taking the piss out of~~ Mocking his fifth self, to his face.) Hey! I'm the Doctor, I can save the Universe using a kettle and some string and look at me, I'm wearing a vegetable!

- It was eventually explained in his final episode as a precaution against a particular poisonous gas.

The Doctor: If the gas is present, the celery turns purple.
Peri: And then what do you do?
The Doctor: I eat the celery. If nothing else, I'm sure it's good for my teeth.

Music

Stage dressing example: French musical duo Justice perform on-stage behind a giant modular synthesizer setup named "Valentine", surrounded by a series of 18 Marshall Cabinets and a giant lit cross. None of this equipment is functional
Non wardrobe example: the one man band Atom & His Package had a gizmo with lights and buttons and levers but it did absolutely nothing. He had it on stage simply because it looked cool (all he used was a guitar and a cd of prerecorded backup music).
Similar to the previous example, Jonah Matranga of Far, Onelinedrawing, and many other projects often performs with a scale model of R2-D2, nicknamed "Are Too". However, it is somewhere in between this trope and Goggles Do Something Unusual because the model also houses a functioning drum machine complete with R2-D2 sound effects, and is used so prominently that tracks such as "Smile" credit the drums to Are Too.
Buckethead wears a chicken bucket on his head. It doesn't contain any chicken.

Video Games

This is the purpose (or lack thereof) of most Nice Hats in Team Fortress 2.
- A select few hats do, however, give a Full Set Bonus.
In RuneScape, among the myriad of armor and weapons, several pieces of equipment offer no stat bonuses whatsoever, such as the Brass Necklace and Cyclopean Helmet, relegated to only serving cosmetic purposes.
Implemented, much to fans chagrin, in the Super Smash Bros. series with Ganondorf's sword. Ganondorf likes to show off his sword after winning matches or taunting, but he never actually uses it. To quote Masahiro Sakurai, the lead developer of Super Smash Bros. Brawl: "What are you putting it away for? Use it! People tend to make fun of Ganondorf for this." Really, though, it seems the developers are making fun of the fans with it.
- A lesser example is how Captain Falcon refrains from using his personal sidearm in the games as well. Doesn't stop him from using Ray Guns and Super Scopes, though.
In Final Fantasy XII, Penelo has these bronze-colored wing-like armlets on the back of her outfit, on the shoulder blades; they don't seem to have any purpose.

Western Animation

Kim Possible: Kim and Ron's commando mission suits in "A Sitch In Time".
- Shego's supervillain outfit has a leg pouch she's never been seen to use.
Bender and many other robots in Futurama have antenna that serve no apparent purpose, which gets a Lampshade Hanging several times. First when the thing turned out to be interfering with the satellite transmission in his new apartment, and Fry says he should just cut it off since it doesn't do anything, after which it's treated as a robot equivalent of his penis. Again when it's suggested he has a toilet somewhere in his body and pushing down on it flushes. Subverted again when Mom says most people think she puts antenna on her robots just to make them "more science-fictiony" but they really let her take control of everything with a remote control.
Super Chicken, from George of the Jungle, carries a rapier, but it seems to be only for show.

Real Life

Jewelry, in general, is this. The vast majority of it has no practical function aside from telling everyone around you how much money you have to spend on pretty but useless trinkets. Historically, it was a way to display family wealth and social status.