Magical Materials

[Gaea]

First off, a disclaimer: you can ignore all of this and have a sword made of a transforming Celestial spirit who is also a 10/10 waifu that also turns into a steampunk motorcycle. None of the below is an attempt to tell you what you CAN make, just some suggestions if you want to go more in depth with where your magic sword came from or how it was made.

Materials
Quality weapons are often crafted from a material aside from base iron or steel, such as the so-called 'Magical Materials'.

• Orihalcum is a rare and powerful material, said to be forged from light itself, but unbelievably durable even by the standards of the magical materials - it is said weapons born from it are truly indestructible. It is very difficult to mine or forge, requiring powerful light magic to enchant its base form, which is only easily located inside active volcanoes and similar dangerous locations. Its rarity and value ensure that what Orihalcum weapons do exist are each works of art, despite the difficulty in crafting even a simple sword with it.
• Mithril is a silverish-green mineral best known for its eerie luster and relative ease of smithing compared to its kin. Weapons forged from it are light as air and are said to be able to cut through anything. While it is mostly found in shallow mines and sometimes on the surface in forests, it is very difficult to find in large quantities, and the odd fact that two hunks of Mithril will almost never play nicely with each other results in most Mithril weapons being either small or slender, forged from a single mass.
• Soulsteel is an infamous material, a metal so dark it seems to consume light, that gains its legendary lustre and power from the souls - often human - bound to it. Weapons forged from it seem to drink in the essence of their victims, growing steadily more powerful over time, but tend to influence their wielders - and rarely for the better. While Soulsteel is at its core simply normal steel, the arcane rituals to refine the enhanced metal are secretive, and on account of the whole 'beating human souls into eternal agony to strengthen your sword' aspect, the real problem is dragging a bunch of still-alive peasants to a smith willing to do that kind of work. Has no relation to the Nether or Abyssals in general.
• Jade is among the most common of the magical materials, split into three distinct colors, each with a strong elemental affinity that lends itself well to magical weapons; Red Jade conducts Fire magic extremely well, Yellow for Thunder, Green for Wind. Other colors of Jade are said to exist as well, such as the legendary Rainbow Jade or the rumored Blade Jade, but are not found in nature - rather smithed, if they do exist at all. Nature and Primordial magics do not lend themselves well to Jade weaponry at all, aside from Earth magic which has a surprising affinity for it. Well liked by adventurers and smiths as well for its availability and ease of smithing, but it is incredibly brittle during the smithing process which occasionally ruins an amateur smith's work.
• Dragonbone is quite controversial; extremely effective at conducting magic, but seen by most dragons as bordering sacrilegious - much the same as if your neighbor started drinking from the skull of your long-dead sister. While not all dragons view it as harshly, many smiths refuse to touch it on principle and most dragonbone weapons have a story behind them - rarely a happy one. Mostly only born by dragons or dragonslayers; everyone else stays well away from them since Jade is infinitely easier to acquire and just as effective.
• Spirit weapons are known to have powerful magic of their own; by binding an elemental spirit to a weapon, usually specially-crafted to enhance conductance though some are makeshift seals in battle to contain dangerous spirits, it becomes possible to have a weapon that can launch magic of its own. Since creating them requires intricate knowledge of both magic and smithing, only a relatively small subset of blacksmiths can combine the two effectively, and the process of coaxing spirits willingly into the metal often requires rare reagents that are generally up to the adventurer to find on their own. Nonetheless, they are a common way for less magically adept hunters to gain some form of ranged offense.
• Aethyrium is an extremely rare and valuable metal forged from the body (or sometimes corpse) of a Celestial - the stronger they were, the better the quality of the blade. Even in death, the spirit's lingering will tends to affect the final blade as much as the smith does, leading to a strong tendency for uniqueness among the often silver-sheened weapons. The special trait of Aetherforged weapons is the lingering will of the spirit it was created from, which can often still affect the weapon to some degree, doubly so for those that still live on within the blade. This can be good or bad - unhappy denizens rarely make for effective swords, but those whose goals align with the wielder seem to move on their own, dancing through fights and intercepting blows that even the wielder did not see coming. Needless to say these weapons require a strong link of trust between wielder and weapon, which limits their mass appeal.