They go by the name "Aalst". They have great power at their disposal, and even moreso when wielded by someone of great skill. Aalst is wielded by Veen Sundown, against the demon and Calamitous threat of the Modern Ertisia age.
Aalst is created by an off-realm magical alloy called Mirakulum (nearly 1,990,000 times more durable than steel, practically impervious), able to take upon aspects and properties of different energies and magic. It is highly flexible with all kinds of magic and enchantments.
Aalst is capable of manifesting from their own blade, being able to wield themselves against other threats that wish to take and use them for their own personal gain.