Stat sticks are weapons carried or equipped by a character primarily or solely for the statistics they give.

This happens when possessing a weapon gives bonuses to a character even if it is not used. In extreme cases, the weapon will provide these bonuses even when held by a character who cannot legally use it. If that sword gives additional MP to anyone who has it in their inventory, then why not give it to your mage? Your mage can't use the sword as a weapon, but he can certainly use the MP!

This also happens when weapons are used to house valuable types of inventory in such a way that more of that type can be carried with the weapon equipped than without. Your character may have the Diamond Sword in his inventory even though he never uses it, simply because it's a convenient place to store power diamonds. May also be used to clear stat requirements for Level Locked Loot.

Examples:

In World of Warcraft, this is a term used to refer to all caster weapons (staffs, swords, daggers, shields and offhands), any melee weapon equipped by a hunter, and any ranged weapon equipped by a melee user.
- This is also true for the relic slot now as they no longer have unique effects or procs and are now just there to give the hybrid classes the same stat boosts that the other classes get from wands and ranged weapons.
- That said, Blizzard recognized this issue and will effectively reduce this by eliminating relics and 'unused' weapons in Mists of Pandaria.
In Torchlight equipping two weapons of the same type doesn't increase the speed at which you fire them, so the offhand weapon becomes useful only for the stats and gemslots it provides you with.
Quite a few loadouts in Team Fortress 2 give a variety of stat boosts/penalties, with whole themed sets giving an extra boost.
- While most characters use their different weapons actively, this concept holds especially true for The Medic, since he only really uses his healing ability. This is the reason why the unlockable Blütsauger weapon is not used by most medics, since its ability to leech health off the victim seldom comes into play as much as its lower health regeneration rate compared to the standard Syringe Gun.
Dragon Age has this trope in the case of dual-wielding backstab rogues. Normally dual-wielding attacks alternate hands, so both weapons are equally important. However, rogues only ever backstab with their right-hand weapon; their left-hand weapon can therefore be used as a Stat Stick.
This is the idea behind Kingdom of Loathing Cheffstaves. Since Mysticality classes attack using spells, attack power is useless to them; Mysticality related enchantments are much more important. Most utensils are weaker than other weapons while increasing Mysticality or spell damage, but the Cheffstaves exemplify it. They all have the same power as the starting weapons, but they great percentile spell damage increases, as well as 2-3 of the following: MP regeneration, bonus power to certain elemental spells, direct and/or percentile Mysticality increases.
Slight variant in Flyff: Billposters carry sticks around, since Assist buffs can only be used with a stick equipped. Thus, if one can afford it and has money to spare, there is no reason not to get one that gives additional MP or INT while it's equipped.
Vindictus: Magic-user Evie starts out only wearing cloth; and building sufficient skills for even light armour is difficult and time-consuming. Since she relies primarily on innate magic armour to avoid being a Squishy Wizard, any armour that she does wear is almost entirely for the stat boosts.
- Also, as of the Labyrinth expansion, Staff Evies can no longer use their staffs for melee, only for magic, making their staffs essentially this.
While most weapons in Demon's Souls give bonuses according to stats (which is the inverse of most RPG weapons), some weapons fall straight into this trope, such as the Kris Blade, which is a medium sword mostly wielded by mages thanks to their magic-enhancing property (while being absolutely useless for melee).
- The Morion Blade is this for a Hyper Mode user. The Adjudicator's Shield is also often used as one, as it provides substantial health regen, but as an actual shield it's kind of cruddy, meaning that most people just wear it on their backs while wielding their weapon with both hands.
This is often recommended for Final Fantasy VI for characters whose effectiveness is not dependent on their basic physical attacks (which is most of them); why does Sabin need the weapon with the highest physical attack power (in the GBA version, the Godhand) when his best skills are all powered by his Magic stat (raised by Tiger Fangs but NOT the Godhand), for instance?
Final Fantasy XI has a number of these, but the most famous of them are the eight level 51 elemental staves. Each of them has a number of significant stat boosts themed around its element (for example, the Fire Staff boosts Attack and the Wind Staff boosts Evasion), as well as far-more-important hidden effects that increase the potency and accuracy of spells of its element at the expense of the same for the element that it beats. Needless to say, any mage worth their salt buys the ele staves and swaps them to match every spell they cast.
Angband has a weapon type specifically designed to do this—the Defender.
Dungeons & Dragons generally averts this trope: most weapon enchantments provide bonuses and special abilities specifically for the action of swinging the weapon. But a few, like 3rd Edition's "defender", do work even when you're just holding the thing. In fact, defender works best this way, since what it does is let you reallocate some of your attack bonus to your defense - if you're not attacking, it's an easy trade-off. (But a common houserule requires you to attack to get the benefit.)