Legacy of the Last War
An alchemy blade appears much like a normal shortsword. Two slender channels form a groove on each side of the blade, and the pommel is built to accept a flask of either Alchemist’s Fire or Alchemists Frost. (It could also accept a flask of acid, Acidic Fire or Alchemists Spark, but a single use of any of these would render the weapon useless.)
When a flask of alchemist’s fire or alchemist’s frost is plugged into the pommel, the weapon is primed. When you strike a target with a primed blade and deal damage, an internal alchemical pump instantly expels the fire or frost through hollows in the hilt and out along the channels in the blade. In addition to taking any damage dealt by the blade, the target also takes damage as if it had been struck by the flask attached to the weapon. Adjacent creatures, including the wielder, are not subject to this damage. If the blade deals critical damage, the frost or fire damage is not multiplied.
Priming an alchemy blade requires an action. When not primed, the alchemy blade deals damage as a short sword.