Mini Scabbard (3.5e Equipment)
From D&D Wiki
Mini Scabbard: This appears to be a typical leather scabbard for a wide blade dagger. But upon inspection the scabbard can hold any single bladed weapon in a nondimensional space allowing it to store far longer blade than would normally be possible. Any blade from a knife, dagger, Longsword, Greatsword, or similar weapon up to and including a over-sized weapons like the Full Blade. When shethed, the hilt of the weapon remains it's original size giving the only clue to on lookers to it's actual size.
Moderate; (DC 20) Conjuration;CL 9th; Craft Wondrous Item, Secret Chest; Cost 500gp + 40 exp
Activation: Continuous Weight: 1 lb. Market Price: 1,000gp