Phase Dagger

Weapon Item deals damage as a normal dagger but once per day on command the item can phase onto another plane and then back onto the material one letting it almost teleport through space. This means you could be throwing the dagger at something BEHIND another creature but seeming like you're throwing it at the creature in front. Also, if the dagger re-attunes while its original owner is alive, the new owner will have to make a saving throw with a DC of 10 or warp to another plane of existence with the dagger. It takes one long rest to attune. Rare (this item requires attunement) [First Owner]

The dagger is black with parallel lines going up the dagger. Between those lines and various symbols and runes to mark other planes of existence. Some are intricate looking with tieflings engulfed in flames while others are simple and look like a basic water drop. The dagger seems to be made of a mysterious metal and light enough that it seems like you're not holding anything. While moving around, the dagger seems to try and avoid your eyesight but it is plainly in view.