Echo Force
Weapon,
Rare
(requires attunement; cost 5000 gp)
Crafting Components
Shards from a shattered magic mirror
While you are attuned to and wielding this shortsword and at your hit point maximum, instead of making a melee weapon attack you can strike at the air to create a blade of magical force. Your blades of magical force are ranged spell attacks that use Strength or Dexterity (your choice), have a range of 30/60 ft., and deal 1d6 force damage. When you are not at your hit point maximum, this shortsword becomes a mundane item.
Source