Blade of the Dervish

Weapon (scimitar), rare (requires attunement)

This magic scimitar is empowered by your movements. For every 10 feet you move before making an attack, you gain a +1 bonus to the attack and damage rolls of that attack, and the scimitar deals an extra 1d6 slashing damage if the attack hits (maximum of +3 and 3d6).

In addition, if you use the Dash action and move within 5 feet of a creature, you can attack that creature as a bonus action. On a hit, the target takes an extra 2d6 slashing damage.