A Rune Stick is a type of alchemical magical weapon created during the Mage Wars that still sees occasional use.
Enchanted weapons, even incredibly basic enchantments done on common materials, are prohibitively expensive for common foot soldiers. A spearhead can be easily and cheaply fashioned from any available piece of iron; but creating one that can hold an enchantment requires melting it down to a liquid as well as several other steps. Creating an enchantment that can cause a ranged effect (such as a spear that creates fire balls) is possible, but far too expensive to arm each member of an infantry.
Creating an enchanted bow, while much easier, still created logistical issues. Skilled longbowmen were rare and difficult to field. Enchanted arrows, throwing darts, or sling ammunition was, again, prohibitively expensive as the process of creating any solid material with magical properties required great effort.
Rune sticks were created to fill this gap. The enchanted part of the weapon itself was made from wood, which could be easily enchanted and covered with runes. The rest of the weapon was a simple metal pipe, with only magic contained in the 'striker'; a component which could easily be mass-produced. Rune Sticks could be made quickly and cheaply by novice enchanters working alongside blacksmiths, with only a little material supplied by more skilled enchanters.
A Rune Stick is a metal pipe open at one end and closed at the other, attached to a wooden stock which is enchanted. A small "striker" links the enchantment on the wood to the pipe. This must be made from a magical material, but inexpensive enchanted iron can be mas-produced for it and later cut and shaped. Usually, a simple release mechanism is used to hold the striker in place, similar to a single-action trigger on a mundane firearm (which indeed most Rune Sticks closely resemble).
The barrel is then stuffed with alchemical ingredients wrapped in a spell-form on a small piece of paper or cloth. These, again, can easily be mass-produced by low-level enchanters. Once the striker touches the tube, the spell is "activated".
The Rune Stick acts as both a powerful ranged weapon and a way to provide magical ability to infantry without risking much more valuable mages.
The most common "load" for a Rune Stick is a large number of small, round stones; and a spell-form meant to accelerate them to high velocity. Since the stones themselves are mundane (iron or lead cannot be used the process of purifying it makes it artificial), they can often pass through magical shields and cannot be stopped by counter-magic.
Loads that produce all sorts of simple spells have been used, including "healing" loads that can reverse injuries.