Sieg's Weapons refers to any weapons used by the Knight of the Dark Glyphs, Sieg Wahrheit.
The Sword of Sieg Wahrheit is a sheathless claymore which holds the magical power of producing lightning, it can cut through both flesh and metal.
The Saintly Sword Indulgencia is a shovel imbued with the "Saintly Sign", and appears in the novel series. This blade is made of mithril and can be strengthened by his comrades.
The Gauntlet of Sieg Wahrheit is a magical gauntlet belonging to Sieg Wahrheit. It is the only piece of armor that he, as a knight, wears, and can generate and fire paralyzing blasts of lightning.