Insert Payment to Use

Ordinary weapons are pretty easy to use. Got a sword, slash with it. Got a gun? Point and shoot. But not this kind of weapon. This kind of weapon requires the user to offer up something in exchange for its use. (It could be Life Energy, an ally or anything of that sort.) This trope is popular in Video Games, as it allows the developers to create a way to limit usage of the more powerful weapons. (Especially Game Breakers.) Can also apply to items or even Mons.

May overlap with Cast from Hit Points. If the payment is too exorbitant, it may result in the weapon/item/Mon being Awesome but Impractical. Compare Powered by a Forsaken Child

Anime and Manga

 * The Forlorn Hope in Yu Yu Hakusho demanded a life in return for its wish-granting powers. Subverted when Yusuke offered himself up instead of Kurama, impressing the spirit of the mirror and causing it to grant Kurama's wish without payment.
 * The Illusion Gate card used by Camula in Yu-Gi-Oh GX required an offer of a soul in order to use. As it didn't exactly require her soul, Camula would 'cheat' by using the souls of people her opponent cared about.
 * The three most powerful Caster Shells in the Outlaw Star universe are numbers 4, 9, and 13. Each of the sages on planet Tenrei can make one type, and they warn that they require so much mana to use that they'll convert some of your life force into mana to pull off their effects. In other words, don't use more than one at a time; you may not live through it.

Card Games

 * The Yu-Gi-Oh! TCG has many cards that have some sort of cost, being it offering a monster as a tribute, discarding cards from the hand, removing cards from play, or paying Life Points.

Live Action TV

 * Friday the 13th: The Series: Some of the Devil's artifacts required that the user pay a price for their use, such as a lantern that found sunken treasure but required the death of one of the finders afterward. There was also a crucifix with a hidden blade that required the user to kill a living person before the crucifix could be used to destroy vampires.
 * In Kamen Rider OOO, the Cell Medal coins the monsters are made of are used to power various weapons, such as the Ride Vendor and the Candroid support robo-critters it dispenses when it's not being a Cool Bike. The machine has an actual coin slot that medals are inserted into before it will transform or dispense a Candroid. The Medajalibur sword uses medals as well to increase its power. OOO's suit is itself powered by Core Medals, the colored medals at the center of the main villains, and anything that uses Cells is generally all the more Badass on Cores, but you get those back.
 * Kamen Rider Birth is an even better example. In addition to having access to the Ride Vendor and Candroids the same as OOO, everything needs a Cell Medal to activate. Need to transform? Insert Cell Medal. Need to activate one of the secondary weapons? Insert one Cell Medal for each. Need more ammo for your gun? Use the attached canister to load in a heap of Cell Medals. Need to fire the Breast Canon (a chest mounted weapon)? Insert one Cell Medal to summon it and at least one more to fire it (more Cell Medals means a more powerful shot). Need to summon Sasori CLAWS (a robotic scorpion formed from combining the secondary weapons)? Insert 1000 Cell Medals (at least for the first use).

Video Games

 * Yojimbo from Final Fantasy X demanded gil first in order to work for you, then again every time you needed to attack.
 * Not always, depending on how much he likes you. If you know his mechanics, you can raise your chances of him using his ultimate One-Hit Kill technique (which can potentially one-shot even ) without paying him a single gil to something fairly reasonable. There's a guide on GameFAQs devoted entirely to his mechanics.
 * The Yoto Swords in Tenchu: Wrath of Heaven require a payment of life to use. There are two ways to meet the requirement: Using the swords to kill living enemies satisfies the payment, but if you don't do that, simply having the swords equipped will slowly drain your life. The upside is that these swords can be used to kill undead enemies, which ordinary swords can't do.
 * The bow in the original The Legend of Zelda game used your money to represent the supply of arrows (presumably, Link used the rupees as arrowheads), while the Magic Armor in The Legend of Zelda Twilight Princess drains your money to protect you from damage. These are likely attempts at averting the usual Money for Nothing scenario.
 * Fridge Brilliance in regards to the whole "rupees as arrowheads" thing above, in that it explains why some monsters will drop rupees.

Tabletop RPG

 * In Dungeons & Dragons intelligent weapons usually have their own special purpose and/or limitation, so unless the wielder serves the same cause, the choices are few: lack of cooperation, constant wrestling of the wills or bargaining. It may demand encrustation and luxury scabbard or "I'll help you to beat that dragon, but then we'll have a big undead-chopping foray".
 * Module I12 Egg of the Phoenix: The sword Chrysomer demanded that its wielder encrust 5,000 gold pieces worth of gemstones on it each month or it would refuse to use its powers.
 * Module WG7 "Castle Greyhawk": In order to use a magical set of stairs (Ascendus' Scandent Coin-Op Acclivity), the user had to pay an increasing number of silver pieces to ascend each step.
 * Daoud's Wondrous Lanthorn. In order to power this artifact, the user had to put thousands of gold pieces worth of crushed gemstones in a built-in compartment.
 * The Ravenloft setting had a giant magical bowl that could allow escape from the plane but required human sacrifice to use.
 * Dungeons & Dragons 3.5: Many magical items have prerequisites such as being evil or worshiping a specific deity; however, they'll usually have a reduced magical effect for those that don't meet the prerequisite or that actively harm opposition instead of acting non-magical.
 * Changeling: The Lost has Tokens, items that have been suffused with the magic of the Hedge. Changelings can activate them by expending Glamour or exerting their measure of the Wyrd, but anyone can activate them if they pay the Catch. Depending on the Token, this could be a pint of blood, your luck at romancing others for the rest of the week, or a handful of dead fireflies.