Cheaper Magic Metals
A brass like metal derived from a magically treated alloy of copper with trace amounts of gold and silver. It shares properties with orichalcum and mithril both, conducting and amplifying magic, but to largely lesser degree. When magic flows through it, it thrums and glows.
Also known as Thunderbolt Iron, it forms naturally in places rich in iron and favored by lightning strikes. Natural lightning strikes do better then induced ones, but enough induced ones can be used in artificial manufacturing. It shares properties with orichalcum and adamant, amplifying and reinforcing magic, albeit to a lesser degree. It will display any magic power inherent to it as faux-electrical sparking.
A steel "characterized by distinctive patterns of banding and mottling reminiscent of flowing water." The secrets of manufacturing it are being lost and attempts to recover them are being made. It shares properties with adamant and mithril, reinforcing and conducting magic. When magic is made to actively flow through it, the patterns on it will shift and move like running water.
Arc of Youth
A duplicable artifact of immense power, a work of greater bioturgic power applied to destructive causes. It's outer shell is a work of intricate wizardry and alchemy meant to compliment a mystical core. It is a casket wrought from an alloy mostly made of corinthiacum and spiked through with mithril and orichalcum as appropriate, creating a matrix of magic that magnify and shape the mystical core towards destructive purposes and safely cradle it.
The core is a newborn baby. The one small fortune is that in the deployment of the weapon, the infant is actually unharmed. When opened, usually after dropped on a city, the casket takes the bursting life of the child and amplified it over the whole city. Building are unharmed and no one immediately dies. Physically, in fact, youth and years are restored to everyone, revealing the original intent of this weapon was that of immortality. However, varying on actual age, it's only a few years up to a decade for the eldest and the horrible side effect is that it effects the mind more, regressing the subject down to an infantile state. So after that, the invading army simply marches in and deals with the degenerated populace however it pleases, after recovering the baby.