Shard of Shar

This crystal can be commanded to
transform in to any weapon.
The users proficiencies still count.
For example if you are not proficient with
greataxes, the shard can become such a
weapon however the wielder will not add
their proficiency bonus to the attack.
The wielder receives a +1 bonus to attack
and damage rolls. On a hit the target takes
an additional 1d4 Necrotic damage