Powerful, but Inaccurate

In the spirit of Competitive Balance, there has to be a drawback for everything. In this case, it means that a powerful attack is more likely to miss it's mark than a weaker one. Now, the reasoning behind this can vary wildly; ranging from discouraging the usage of a particularly powerful move to simply encouraging people to try something else. But sometimes, this trope can be driven to the point where one's Improbable Aiming Skills can't provide a remote opportunity of landing an otherwise fatal hit. *cough* Fire Emblem *cough*

For clarity, as an sub-trope of Necessary Drawback, this trope counts if an weapon or attack has an noticeably high probably of missing and is stronger than most of your arsenal. If it's solely the fault of the user, blame them for graduating from the Imperial Stormtrooper Marksmanship Academy. A-Team Firing is when this applies to everyone wielding the local equivalent of a rocket launcher. Awesome but Impractical is related to this if a more accurate and weaker attack turned out to be more reliable. Inverse Law of Sharpness and Accuracy is when attacks can't hit living beings because they'd be lethal or draw blood, yet are perfectly accurate against robots.

This is also related to Difficult but Awesome when the Random Number God is actively working against you and you're winning behind this. Fixed Forward-Facing Weapon is when your your accuracy is affected by the direction your weapons are facing. And Always-Accurate Attack is the opposite of this when your attacks are weaker than usual in exchange for a guaranteed hit.

Tabletop Games

 * The Power Attack feat in all D20 System based games allows a character to raise their damage in exchange for lowering defense. Since in most games using it accuracy raises automatically while damage does not and two-handed weapons get a better than one to one conversion it's considered mandatory for anyone who wishes to seriously engage in melee combat and doesn't have some alternative source of damage.
 * Enforced by Mutants and Masterminds. The combined accuracy and power of an attack can't exceed twice the series power level. The primary way around this is to make an attack also have an effect that also weakens the target's defenses (like a fire blast that also melts armor) since Weaken effects aren't touched by the cap.
 * GURPS has an "extra effort" mechanic that allows you to trade skill for power -- pay 1 Fatigue and for every point by which you lower your skill on a specific roll, you gain an extra 10% in output (for those skills where that is meaningful, such as spells or psionics); this also works for attribute rolls, particularly Strength. Since skill rolls of 17 or 18 (on 3d6) are automatic failures anyway, the usual "stop point" for reductions is an effective skill of 16, but it's possible (and legal) to trade off control for output even further.

Video Games

 * Dragon Quest: Whack, Thwack, and Kathwack are all recurring instant-death spells in the series. Aside from certain monsters being resistant to them, the only other drawback to these spells is their low accuracy.
 * Fire Emblem:
 * Generally speaking, the stronger a weapon is, the less accurate it becomes. This is particularly noticeable in The Binding Blade since in that game player units are underpowered and most weapons are quite inaccurate in the first place (e.g., a steel axe has a base 50% chance to hit, but 65% in the next game).
 * And compared to swords and lances, axes are less accurate, but they're more powerful (the degree depends on which game is being played). Dark Magic and Thunder magic are also this way when the magic types differ.
 * The Gamble skill increases critical hit rate while decreasing hit rate. It's only worth it on units that have perfect hit rates already.
 * Pad from Nostalgia can learn a One-Hit Kill ability called "Dead Shot," which is significantly less accurate than the rest of his offensive attacks.
 * World of Tanks:
 * SPGs (self-propelled guns) are prone to missing by an wide margin, on account of their shells harmlessly landing in front or behind their targets. But when they directly hit an tank from a favourable angle, the results can range from Scratch Damage, simply taking a sizeable chunk out of a vehicle's health, killing a tank with one hit, and even a One-Hit Kill or One-Hit Polykill.
 * While there are many tanks that can equip a canon that fits this archetype, the KV-2 with the 152mm M-10T howitzer is infamous for: Shooting at the ground in front of an enemy tank who's 50 meters away from you, destroying most of the opposition it sees with a single high-explosive shell, severely crippling an enemy tank when said shell doesn't completely penetrates (which is common), and completely missing an nearby enemy only to kill another one that's a fair distance behind it.
 * In Pokémon the "best" attack moves of a type has at least two candidates, one of "normal" power but perfect accuracy (unless accuracy is decreased by effect) and one of higher power but only 70-80% accuracy. Most serious players generally prefer the first, but the second is often needed to pass certain 1HKO thresholds or because a Pokémon simply can't learn the first one. Most moves that hit regardless of accuracy changes tend to have half (or less) the power of standard attacks.
 * One particularly extreme example is High Jump Kick which is very powerful at 130 attack (in gen V onward) and 90% accuracy. In exchange, if the user misses they lose half their total HP.
 * And there's also the One-Hit Kill moves, like Horn Drill; which generally have an accuracy of 30%, gradually become more accurate if the user is a higher level than the target, and automatically miss if the target is a higher level than the user.

Real Life

 * Barrel length in firearms allows the expanding gas more time to propel the bullet to speed, but longer barrels are harder (but by no means impossible) to make accurate. This generally isn't noticeable past R&D since almost anything that truly needs the accuracy will also need the increased range the faster bullet has.
 * Early (In and around World War II) semi-automatic rifles were far less accurate than the bolt action rifles that proceeded them. The US, Germans, and Russians all tried and quickly abandoned the idea of using them as sniper rifles.
 * The M14's 7.62x51 is far more powerful than the M16's 5.56x45 that replaced it (gradually enough to be seen alongside it), but the M14 was far more inaccurate. This was almost entirely a result of the M14 having absolutely dreadful accuracy than anything. This can be seen in scaled down 5.56 M14s (Mini-14) and the M16's 7.62 predecessor (AR10).