The most recognized sword of The Realm was the preferred weapon of the noble families of The House of Hart for millennia. Althoug glys means “swift” in Iowyd (High Wyddic), it is not the true origin of the common name for the sword. “Glissknife” comes from translations from the wyddic languages; it was called the gwyderbás or ‘death-glass’ in Draechi (Low Wyddic) or the cleygwydor or ‘glass-sword’ in Iowyd (High Wyddic). "Glass sword" lead to an absurd but lasting speculation that the first wyddans used swords of obsidian from their now-sunken homeland. But "glass sword" and "death glass" likely have their origin in the blade once having been known for being polished to an extreme and long lasting sheen in the style of elvish blades. The elves were known for using terrifying and gleaming blades, fast and difficult to see in battle. Stories from the House of Hart tell of ancient mythic battles where the high elves always vanquished their foes with the sun in zenith and with the warriors of Caer Sidi casting blinding reflections by using blades that were otherwise as invisible as polished glass. Byddic cyn e temlo cyn i cayweld! "Feel an elf's anger before you see it!" was a High Wyddic phrase warning against elven wrath.

The shape of the glissknife is clearly of high elvish influence though it is unknown if this influence came from associations between humans and elves in the time of Caer Sidi or if the shape was copied from the manuscripts of elves discovered by wyddans returning in The Realm after the fall of Caer Sidi.

The glissknife's use by Iowyd speakers is confirmed as far back as the 12th Century B.E. where the the sword makes an appearance in the Cleddig Tapestries of the City of Dumnonia. Here several glissknives appear sheathed in the hilts of warriors sailing back to The Realm from across the Western Sea. No matter how far back the wyddans' use of the glissknife goes, certainly further back than the formation of The House of Hart, probably further back than the founding of Dumnonia and maybe as far back as the Sylvan Age, the glissknife is easily the most ancient surviving blade design in Realmic history.

Known more by their shapes today than their iron, true glissknives in the time of Dumnonia were forged of The Silver of Glarseach: an alloy of Iron and Drachtite with various sources of carbon added to make the alloy lighter in the hand and capable of holding a long-lasting and glass-like sheen.

A glissknife is used with deadly accuracy by sword masters familiar with the ancient elvish style of combat. The subtle downcasting curve of the glissknife is its most elvish archetecture allowing it to be used as a thrusting or cutting weapon when held in an elvish-style grip allowing the user to flip the blade up or down without changing the hand position from prone to supine. The subtle concavity of the cutting side is used by a trained fighter to easily disarm an opponent or even remove their entire offending hand. Some who still hold ancient grievances against the cruel elves of Caer Sidi say the concavity of the blade was a throat-cutting feature used to dispatch thousands of captive combatants without the elves having to overtire their gracile hands.