This paper model is the Eternal Edge, Eternal's primary combat knife that is summoned through the powers of the Eternal Memory, based on the Kamen Rider series, the papercraft is created by [unknown].
When the Eternal Memory is placed in the weapon's Memory Slot, it initiates the Eternal Requiem Maximum Drive, which disables the original Gaia Memories. With the Eternal Memory, it can initiate the Bloody Hell Blade Maximum Drive, where a glowing blue sword beam is released from the weapon. When the Zone Memory and Eternal Memory are respectively placed into the Maximum Slot of the Lost Driver and the Memory Slot of this weapon, it initiates the Eternal Never End Maximum Drive, where a huge ball of energy is formed above Eternal and drops onto the opponent. [Source: wikia]
You can download this paper model template here: Kamen Rider - Eternal Edge Knife Free Paper Model Download [Box] [Gavitex]