In Mystery of the Emblem, there are several Dragonstones, which are the Fire, Earth, Flying, Ice, Mage, Divine, and Dark (Unused). Rather than being used as a weapon, they are items that would transform the user in to the corresponding dragon depending on the stone used (ex. Firestone into a Fire Dragon), where the user would be that dragon type for a number of turns. In this state, they used unlimited breath "weapons" that corresponded to the dragon type. Enemy dragons would remain dragons after using a stone for an unlimited amount of time.
In Binding Blade, Fae is a Manakete who has a Divinestone, other manaketes also appear wielding Firestones.
In Rekka no Ken, there are no playable Manaketes (Ninian and Nils' Dragon forms are not playable), and thus, there are no actual Dragonstones within the game. However, Ninian and Nils retain their Dragonstones within the story, allowing them to transform.
In The Sacred Stones, Myrrh owns a Dragonstone that has 50 uses. This Dragonstone cannot be repaired by the Hammerne staff.
In Awakening, Dragonstones, along with Beaststones, are treated as weapons instead of items more than any previous game, complete with their own actual weapon type and weapon type icon in addition to their weapon-like stats seen in previous games.
In old development notes for Genealogy of the Holy War, it is mentioned the sacred weapons are made from Dragonstones and also suggests the Falchion from Akaneia is as well, but the games do not incorporate this element. This idea would also contradict the fact that Falchion was from one of the fangs of Naga.