Using the powers of transmutation magic, you shape the water vapor in the air around you to form a blade of pure ice in your hand. This magic blade lasts until the spell end. It counts as a magic simple melee weapon with which you are proficient. It has the light and finesse properties, dealing 1d8 piercing or slashing damage (your choice when you cast this spell) plus 1d10 cold damage. In addition, hen you score a critical hit against a target with this blade, the weapon shatters and explodes, dealing 3d6 cold damage to every creature within 5 feet of you (not including yourself). 

If the weapon explodes, or it is no longer in your hand at the end of your turn, it melts. Thereafter, while the spell persists, you can use a bonus action to cause it to reappear in your hand. 

At Higher Levels. When you cast this spell using a 3rd- or 4th-level spell slot, the cold damage increases to 2d10. When you cast this spell using a 5th- or 6th-level spell slot, the cold damage increases to 3d10. If you cast the spell using a spell slot of 7th-level or higher, the cold damage becomes 4d10.