Blade Mirage

You touch the weapon used in the spell's casting and imbue it with illusory magic. When you cast the spell as a bonus action on subsequent turns until the spell ends, you can cause illusionary copies of the weapon to assault a creature you see, forcing it ti make an Intelligence save. On a fail, you gain advantage on the next attack you make with the weapon against the target before the end of the next turn.

As an action, a creature that sees you can make an Investigation check against your spell save DC. If it passes, you don't have advantage anymore.

Creatures that are blind don't rely on sight to perceive their surroundings (such as with blindsight) or can see through illusions (such as with truesight) and are immune to this spell.