Prismarine Blade

The Prismarine Blade is an Sword that can be crafted after reaching Prismarine Shard Collection tier II. It is not recommended as a weapon due to its poor damage and strength. But, the only good side to this weapon if you are running Floor 3's and can go in the water, which will deal 200% more damage. Overall, you should not be using this weapon whatsoever.

Crafting
Crafting Recipe for the Prismarine Blade:

Prismarine Shards
海磷刃